
Class $67? 



Book 



10 



COEflUGHT DEPOSIT. 



The Use §f Explosives 

for 

gricultural and 
Other Purposes 



4B& 



Published by 

The Institute of Makers of Explosives 

103 Park Avenue, New York City 



ftsp 



The Use gf Explosives 
for Agricultural and fs-u 
Other Purposes 




Published by 

The Institute of Makers of Explosives 

103 Park Avenue, New York City 



Copyright, 1917, by 
The Institute of Makers of Explosives 



MAY 28 1921 
©CU614734 



03 




How weeds and briars grow up about a boulder in a field. In this case the stone itself is not very 
large, but the total land area put out of business is three times as much as the stone covers. 



INTRODUCTORY 

THIS bulletin is published by the Institute of Makers of Ex- 
plosives. The aim is to give the united conclusions and the 

sum of the experience to date of nearly all makers of explosives 
and of farmers who have dealt successfully with the problem of 
the uses of explosives on the farm. 

The material has been classified and assembled so any phase 
of it will be available easily and quickly. Uncertainties have been 
eliminated as much as possible in favor of known facts and formu- 
las established by actual experience. It is offered as a manual or 
handbook for farmers, home and road builders, contractors, park 
makers and others who must remove rocks and stumps from land, 
and as a textbook for students of agriculture. 

Readers will find that the recommendations are impartial, and 
that the suggestions on that part of the work which can be done 
best with explosives are particularly complete. 



Boulders and Ledges of Rock 

Eight generations of farmers have picked stones off the fields of a great 
many farms in this country, and in these same fields all the boulders too big 
to be moved by the direct strength of men and horses still are dodged by the 
present farmers. Some land cleared and farmed as long ago as the Revolu- 
tionary War has not had the " niggerheads " removed to this day. 

Those stones that project above the surface of the ground can be avoided, 
but those hidden underneath are more serious trouble makers. The man who 
works his own land for years gets to know where they lie, and can escape them 
to a certain extent, but it is by broken plowshares that a new plowman learns 
their location. 

In former years, before the value of land began to increase as it has of 
late years, farmers found more profit in locating a new acre that had fewer 
stones or none at all than in removing those from a stony acre. But that time 
is past. Farm land today can be made to pay without removing the boulders, 
but a far greater return can be had if they are removed. Stony farms can be 
sold, but not for big prices. Thoughtful farmers remove the rocks. 

It is surprising how much there is to know about the disposal of boulders. 
Too often this work has been attempted in ways that were crude and wasteful 
of energy and time, and considering these items, very expensive. This is partly 
due to the lack of published data describing easier, simpler ways. The up-to- 
date farmer will not tolerate methods that are wasteful or unprofitable. He 
may find the information he wants in the following pages. 



The Profit and Loss Account of Boulders 

The interference of boulders and rock ledges with farming operations and 
profits takes many forms, and its cost can be estimated from a glance at a few 
of them. 




This is the sort of perpetual tenant which pays no rent, and on which this bulletin declares war. 

4 



On ground where a cultivated crop is grown, each boulder causes the 

waste and loss of about half an hour per year of the time of a man with a team, 

worth five dollars a day. Four seasons' loss will remove the 

Time Lost stones. They "eat their heads off" as the saying goes, ten or 

more times during the active lifetime of the average generation. 

In addition, the breakage and damage to tools and machines may amount 
to as much in total loss as that from waste of time. This is particularly true 
of those farms where modern heavy implements are used, as, for instance, the 
heavy disc harrows for four or more horses, the gang plows, and all the tillage 
tools pulled by traction engines. Tractor plows and harrows are sure to be 
broken in stumpy or rocky land. It is impossible to make good time with gang 
plows or harrows among boulders, because of the constant stopping necessary, 
and besides, the work done is bound to be poor. Ten to twenty boulders to 
the acre are just about as bad as 100 for the man with the engine imple- 
ments — they make good work and speedy work impossible. 

About each rock that sticks above the surface some weeds are sure to 

grow. There never is the stone, or log, or stump, on or in 

Weed Breeding the ground but where you can find a thistle or two, or 

several specimens of other equally noxious plants, growing 

close to the edge or out from under it. These single weeds re-seed entire fields. 

Another feature of the loss sometimes caused by tight stones in fields is 
the injury to horses and men caused by the sudden strain and jerks. Horses 
sprain leg joints, shoulders, hips and backs. Many 
Danger to Horse spavins have their beginning in the ugly twists sustained, 
and Men Brood mares often are caused to lose their foals prema- 

turely. The baffling for which stones are responsible is 
one of the most common causes of balkiness of farm horses. A team can be 
ruined in a short time by such treatment. 

The danger to men is not so common, but when it does come it comes 
heavily. The records of the past generation show that many a farmer was 
struck with a plow handle when the plow point encountered a stone that was 
tight. Sometimes the result is a broken arm or hip, or rib, or worse still, a 
rupture. The newspapers frequently report accidents caused by the driver of 
a mowing machine being thrown from the seat into the knives, or under the 
heels of the horses, when the machine suddenly struck tight obstructions such 
as stones. 

The direct loss of* crops which would grow on the land occupied by the 
boulders need not be stated in figures. Every farmer knows that the loss of 
corn, wheat, or hay on a square rod amounts to 1 5 to 50 cents a year. 

Tight stones on a farm are bound to keep its selling 
Low Land Value value down. One of the first things a shrewd buyer of 
and Increase land will want to know is whether the soil is free of rocks 

that interfere with cultivation. One of the easiest and 
surest ways of increasing the value of land, for selling, for actual use, and in 
the estimation of other people, is to clear away the boulders. 

The stones themselves may not be without value when they are broken up 
in pieces small enough to handle. It is well for every farm to have a pile 
in some convenient place, where they can be had any 
Value of Stones time they are wanted. They are valuable for building 
material, and in drains and walks. At the rates prevail- 
ing in many places it is easy to collect fifty dollars' worth of stone right 

5 



near where it is needed and save both the cost of the stone and most of the 
expense of hauling. 

Some of the more common purposes for which stones are valuable on farms 
are for blind drains, for lining ditches along roads or in fields, where the water 
gouges out the sides or bottom on account of a grade or turn, for road founda- 
tions, for repairs to walks, for constructing steps, chimneys, walls, etc., for fill- 
ing in concrete construction, and for building garages, houses, barns and silos. 

Clearing land of boulders should not be regarded as an expense, like taxes, 
or like the cost of shoes to wear. It is an investment, like the purchase of 
Government bonds, or like the purchase of shoes by a storekeeper, to sell 
again. When money is spent for removing boulders by a farmer, he is buying 
something — the clean land — that at once begins to pay back the cost of the 
work. It pays for itself within three or four years and then keeps right on pay- 
ing dividends year after year. 



Kinds of Rock and Their Nature 

It helps if you know your rock when you go to break it up, for many 
different kinds exist as boulders and ledges on farms and in roads. In some 
sections the term "hardhead" is used to describe one kind of boulder. Another 
term is "niggerhead." It is better to know the rocks by the names which 
designate their real nature. 

Rock Qualities 

What does make a difference is that some stones are easy to break and 
others are not. To understand why, a study of the stones is necessary. Their 
resistance depends on their comparative hardness and toughness. These two 
qualities must not be confused, for they are not the same. 
Hardness and To illustrate, window glass is hard, but not tough. It will 
Toughness scratch very hard steel, but will shatter under a light blow. 

Untempered iron is tough, but not hard. It can be ground 
away rapidly by a stone, or scratched with glass, but it is extremely difficult 
to break by pounding or twisting. 

To some extent stones possess the same qualities, and in addition almost 
all of them have one or more lines of weakness. Most rocks have a grain, not 
unlike the grain of wood, and will split more easily along the grain, and less 

easily in any other direction. It is 
safe to say that all rocks have 
joints running in one direction, and 
some rocks have two sets of joints 
running at right angles. The joint 
lines may not be visible, but the 
force of a blast or of a sledge will 
find them. There is still another 
sort of weakness in rocks with 
which the blaster should be famil- 
iar. This is the bedding plane, 
or layer — with lines running at 
right angles to both joint-lines 
mentioned. 

Some knowledge about the 
joints and natural cleavage planes 
makes the breaking of rocks easier. 
Even the most massive rocks are 
divided into blocks of varying sizes, 
making them split in some direc- 
tions easier than in others. The 
cracks will tend to stop short and 
splinter out or to run entirely 
through the stones, depending on 
the toughness of the rock, while 
the blocks will or will not crumble 
much according to their hardness. 

Description of Rocks 

In these brief remarks we will make no attempt to give the geological 
classification of the rocks, but will try to identify the typical rocks found as 
boulders and ledges by names which are used most generally, and to make 

7 




How the seam and joint lines crisscross in most 
stones. A little inspection of a stone nearly always 
will show a spot where the force can be applied to 
break it with much less force or greater effectiveness 
than if the stone is attacked at solid spots. 




Two fields which will cost $50 to $200 or more an acre to clear of stumps and stones. If the land 
can be used for residential purposes or for some form of intensive farming like trucking or fruit growing, 
it will pay to clear such places, but it will not pay to clear them for general farming and pasture purposes. 



clear their nature. Common names for different kinds of rock or stone are 
not always satisfactory because the common name applied generally to one 
kind of rock in certain localities in numerous instances is applied to an entirely 
different kind of rock in other localities, but it is hoped that any confusion 
will be limited. 

These three classes of rock seldom exist as boulders, though they some- 
times interfere with cultivation in the form of ledges close 
Talc, Gypsum to the surface of the ground. In this shape they nearly al- 
and. Shale ways are full of two sets of joints, and lie in thin beds. Some- 
times the seams are so close together that the rock breaks 
up into blocks only an inch or two square. They are fairly tough, are inclined 
to crumble rather than split or crack, when struck with a sledge hammer, and 
are easy to drill. 

Usually takes the form of flat boulders on the surface in fields or of ledges 
which project almost to the surface or above the surface several 
Limestone feet. Limestone generally has two systems of joints. It also has 
bed lines wide apart — -a foot or more. This kind of stone nearly 
always is tough, breaking off, rather than splitting far. Its hardness varies. 
The boulders of this class frequently are nearly round. Slate rock is char- 
acterized by a thin shingle structure. The leaves are less than a quarter 
Slate of an inch thick. There are joints as well. The stone is tough, break- 
ing only a short distance (but splitting on cleavage lines easily), soft, 
and inclined to crumble. 

Occurs as boulders of every shape and size, and as ledges of all sorts. The 
ledges usually are stratified — that is, in beds of a thickness of 1, 2, 3 or more 




See picture on preceding page 



feet. It has frequent joint lines running in two directions, and it breaks up 
into irregular sized blocks of more or less rectangular shape. The 
Sandstone sand particles which compose the stone are very hard. When 
the cementing material is silica the stone is blue or white, and 
much harder than when of an iron origin, making a brown or red stone. For 
purposes of drilling, blue sandstone must be classified as a hard rock, and 
brown sandstone as softer rock; and for breaking purposes, both kinds may be 
listed as soft. It crumbles easily, and is rather tough. 

These rocks and others like them in structure lie 
Lava, Mica Rocks, in layers from 2 to 100 feet thick. They have no 
Feldspar other bed lines, but they have infrequent joint lines. 

Lava, excepting that of the pumice type, is hard and 
brittle. The boulders split fairly easily into pieces of irregular shape and size. 
A mixture of various rocks, such as slate, sandstone and the like, often in 
the form of pebbles cemented together, making a rock that lies in beds. It 
may be crystalline and very hard — even flinty — or it may be 
Conglomerate only medium hard. The boulders are rather brittle than 
tough. Joints in one direction are located wide apart. Boul- 
ders of conglomerate rock sometimes have a ball-like structure, with layer 
after layer 1 to 6 inches thick, and joints every 2 to 4 inches. The layers of 
such rock crack off like the skin of an onion. 

Occurs often as boulders, though frequently there are granite 
Granite ledges. Granite is of a massive structure, with frequent joints. It 
splits easily. It is hard to drill. Some granite breaks easily while 
Other is difficult to shatter. 

9 



Some rocks are full of irregular cavities resembling 
General Features bubbles, and these generally make the breaking easier. 
The cavities interfere with the regular joint lines and 
cause the splitting to take place along new lines of weakness. 

The amount of force required to break a rock depends on its hardness and 
its relative toughness, and on the lines of weakness or cleavage which run 
through it. Hard rocks usually crumble less easily than soft rocks, but generally 
split better when once started. Tough rocks are hard to split into small pieces, 
while brittle ones shatter to bits under a proper blow. 

The point at which the force should be applied for the most and quickest 
breakage depends on the structure of the rock and the direction and frequency 
of bedding and joint lines. 



10 



Methods of Clearing Away Rocks 

Rocks too large to be pried out and loaded for hauling by hand, and tight 
ledges, must be broken. Following are described eight methods of breaking 
them. Each method has advantages under certain conditions, but some are much 
more serviceable, convenient and easy than others under most circumstances. 

List of Methods 

Hauling: Consists of either dragging with chains or 
Eight Methods loading on sled or wagon. See page 31. 

Sledging: Consists of hammering them into pieces 
small enough to handle. See page 14. 

Burying: Needs no description. See page 14. 

Plug and feather breaking: Intended for splitting out building stone. 
Consists of drilling a series of small holes in a line across a boulder, and then 
driving into these holes special steel wedges. 

Blasting by drilling: Called " blockholing " when referring to boulders. 
See page 23. 

Blasting by undermining or underdrilling: Called " undermine blasting " 
or "snakeholing." See page 19. 

Blasting by mudcapping: Also called "doby shooting," "plastering" or 
"blistering." See page 15. 



Choice of a Method 

In the practical handling of rock clearing, the elements 
to be considered are the costs of labor and material re- 
quired. These are governed by the nature and amount 
of rock to be broken. Time is also an important factor. 
The softer and more brittle boulders, if they are not large, may be dis- 
posed of by any of the above methods. Very hard and tough rock cannot be 



Cost, Men, Time 
and other Factors 













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How a boulder can mar the appearance of a farm from the roadside view. Such a stone leads possible 
buyers of a place to think that the field contains many such. 




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The disposal of this partly buried boulder called for rolling it out of its bed in the ground without 
breaking it, and then mudcapping it. It was rolled out with one cartridge from the position shown in 
the first picture, and (see next page). 



sledged into pieces successfully. When such rocks are to be blasted they should 
be drilled (blockholed) rather than mudcapped or undermined. Ledges of rock 
always should be broken up by blasting drilled holes. The limits of size of rock 
at which mudcapping becomes impracticable are explained on page 1 5. 

Labor conditions are important. On some farms men are very scarce and 
wages are high. At other places there are periods when laborers are practically 
idle and can be put to disposing of stones, without much extra cost. In the 
former case it is wise to let explosives do all the work possible with no more 
drilling, sledging, handling and hauling than absolutely necessary. In the 
latter case the amount of explosives used should be kept down, and the idle 
men left to do the resulting extra work. 

The time element is equally important. If nothing else demands the at- 
tention of the men on the farm, a slow method is all right, but when stones must 
be removed in a hurry, the quickest method probably is the cheapest in the end. 

When the cost must be kept down as much as possible, and when easier 
and better methods are not available, burying and breaking by fire may be 
resorted to, provided there is labor available at little cost. Sledging, when 
practicable, is a cheap method if labor and time are not considered, provided 
good sledges are available. But it is slow, hard work. This applies to any 
way of disposing of rocks except blasting. If the conservation of energy 
as well as of time and men is desirable, the use of high explosives is the only 
method to consider. 

Mudcapping is the easiest way to blast boulders in most instances, but 
takes the most explosive of the three blasting methods. It seldom should be 
attempted with boulders containing more than 5 cubic yards of stone unless 
they are thin slabs, and is expensive with trap rock or other very hard and 
tough material. Rocks should be flat rather than round, or at least should have 
a flat side on which the charge can be placed. 

12 




mudcapped a few days later with five cartridges with the result shown in the second picture. Note 
that the entire rock has been reduced to small fragments requiring no further handling. 



Undermining or " snakeholing " has practically the same effect as mud- 
capping, though it requires less explosives and, usually, a little more work. 
Blockholing, though effective and economical, requires time and tools to drill 
the holes. 

Mudcapping and undermining are pre-eminently the methods to use 
where there are only a few boulders to dispose of, since one man can 
do in an hour by these methods what it would take much longer to do 
by any other method. Stones that are deeply imbedded should be under- 
mine blasted lightly to roll them out, or at least to loosen them, before they are 
mudcapped. Some very large stones should be both undermined and mud- 
capped, with two or more charges fired simultaneously with an electric blasting 
machine. 

Other combinations of methods will suggest themselves to a resourceful 
blaster. 

Study the rock. If it is imbedded, roll it out by undermine blasting as 
above directed, and* examine it on all sides. Usually you will find that an 
undermined or mudcap blast, unless the charge of explosive has been small, 
will break up the boulder and make blockholing unnecessary. 



13 



Detailed Directions for Disposing of Boulders 

Small boulders, weighing only 1 00 pounds or so, may be dug out and rolled 

into wagons on planks, or dragged off the field with chains. With 

Digging Out larger stones, hauling is slow business, and is likely to result in 

injury to men. The hard straining required to lift the rocks, 

added to the danger from the falling of heavy stones, makes what would seem 

to be one of the simplest and safest of jobs an exceedingly hazardous one. 

A practicable method of disposing of rocks is to break 
Sledging Rocks them up with sledges. Use heavy sledges — the heavier the 
better. The tough rocks are almost impossible to break in 
this way. It is impractical to sledge up large rocks of any kind. 

Pay particular attention to the direction of the grain and the lines of 
cleavage. A blow right at a vita*, point often will break a rock in two when 
you could hammer away an hour at another part without much effect. 

When you sledge rock, there is much danger from flying bits of stone, and 
it is a good plan to wear gloves. Tie your coat sleeves over the gloves or the 
gloves over the sleeves, turn your collar up, wear a cap which pulls down over 
the ears, and wear goggles. If you have no goggles, be careful to shut your 
eyes when striking the rock. 

One way is to dig a pit alongside the stone, and tip it over. This is suit- 
able for stones that can be pried over. Large stones must 
Burying Rocks be undermined and let sink down slowly. Let each end 
down separately. Extreme care must be used in this oper- 
ation to prevent the rock from roiling on the man who digs. Burying heavy 
stones is a dangerous operation, and has crippled and killed many a man. 

Burying rocks is open to the objection that at some time the work may 
have to be done over again, on account of not getting the top low enough. 
Frost, erosion, and other forces gradually have the effect of bringing the stones 
to the surface. If the rock is large, it will interfere seriously with the growth 
of anything planted over the spot. Buried stones are beyond your reach if 
needed for building purposes. 

The easiest way of breaking stones is to do it with high ex- 
Blasting plosives. The directions for this work are here given in full detail, 
with careful attention to mudcapping, blockholing and undermining 
or "snakeholing," and to combinations of these. 



14 



Blasting Boulders and Ledges 

All of the methods described in the preceding chapter are more or less 
useful, but in actual practice the disposal of boulders or ledges nearly always 
will be impractical unless you use explosives. 

Mudcapping Roc\ 

Briefly, mudcapping rocks consists in placing the explosive in a neat pile 
on a face of the rock, covering it with about 6 inches of stiff wet clay, and ex- 
ploding it. When done right, the force of the explosion breaks the rock. 

It is the enormous speed of the gases which accounts for the success of 
such a blast — the time element. Mudcap blasting is made possible by the 
intensely fast shattering action of some of the modern high explosives. It can- 
not be done satisfactorily with black powder nor with the slower kinds of high 
explosives. 

Owing to the resistance of the air and the inertia of the material in the 
mudcap, the gases strike the rock like an enormous sledgehammer swung at a 
rate faster than the eye could follow. Such a blow, if in proportion to the size 
and strength of the stone, is sure to shatter it. 

Of the three distinct methods of blasting, mudcapping is 
Description the best one to use when the boulders to be broken are flat and 
brittle and smaller than 5 or 6 feet across. 

Probably the most economical mudcapping per cubic yard of rock is in 
blasting sandstone boulders having flat sides, and containing 4 to 6 cubic yards. 
Some sandstone is brittle, yet hard to drill, therefore should be broken by mud- 
capping. Shale, slate, conglomerate and other such rocks break very success- 
fully under mudcap blasts. Mudcapping is less satisfactory, owing to greater 
quantity of explosives required, when very hard and tough rocks such as trap, 
etc., are to be broken. In fact, mudcap blasting had better not be attempted 
on hard, tough rocks that are more than 3 feet in diameter unless no drills are 
to be had, and the stone must be removed immediately. 

If the stone lies free on the surface, it is ready for the placing of the ex- 
plosive. If it is buried in the ground more than a foot, it is a good plan to dig 
or blast away the dirt before attempting the mudcap blast. One way to do 
this is to dig a trench round the stone, to within a 
Preparing the Rock few inches of its bottom. Another way is to place 
one or more small charges down alongside the stone 
and to loosen up the dirt or throw it away from the sides, but in such a way 
as to leave the ground firm and undisturbed underneath. A third, and probably 
the best way where the stone is almost buried, is to explode a slightly larger 
charge down under one side of the stone to roll it out of its bed, and onto the 
surface of the ground. Then it is ready for mudcapping. 

In determining the best point at which to place the explosive, considera- 
tion of the principles of rock structure, as outlined on pages 7 and 9, should 
be the basis. Study the make-up of the rock and de- 
Locating the Place termine the directions in which it will split the easiest. 
for the Charge Look for and work for the hair-thin but far reaching 

seams. Clean the dirt or dust from likely-looking 
places. The joint lines most of the time will be hardly visible, yet they are 
important if the most complete and economical breaking is to be secured. 

Some workers say that they put the explosive where they would hit the 
stone with a sledge if it would be possible to break it with one blow. The big 

15 



thing is to get the explosive at a vulnerable point on the rock, whether this is 
top or sides. It may be necessary to support the explosive and its covering of 
mud with a banking of dirt, or with props from the ground, if the charge has 
to be located down along the side. 

It is better to place the explosive in a depression or hollow on the stone, 
or at least on a flat face, than on a round or bulging surface. A round face 
acts to some degree as an arch, and resists the blow of the explosive much more 
than a flat face. A depression gives the explosive some confinement that en- 
ables it to do better work. 

In placing the explosive it sometimes is well to deepen crevices or de- 
pressions with a drill or cold chisel, in this way making what might be called 
a semi-mudcap out of the blast. Such a blast is more efficient than when the 
explosive is placed on a flat or rounding surface. If it is desired to break the 
boulder or rock into pieces of certain shapes and sizes, make channels across 
the face with a chisel or mason's hammer and place the explosive in these 
channels. The process is like breaking ice by chopping channels across it. 
This treatment gives rough dimension pieces, but it may increase cost. 

The charge of explosive ordinarily should be placed in a low cone at the 
point selected on the rock. If less than four cartridges are to be used, it is well 
to take all the explosive, except ^ cartridge for priming, out of the paper wrap- 
ping and press it into place. If the charge is large, one or 
Putting the more of the cartridges can be left intact and bedded in 

Charge in Place loose explosive. Sometimes the cartridges bed-in better 
when cut in two. The explosive should not cover much 
area on the stone, since widely spread charges tend to distribute their force and 
have lower breaking ability. Sometimes it is a good plan to place the explosive 





How a mudcap charge is pressed down on a flat side of a boulder, with fuse projecting from the mud, and 
how a boulder is broken up. This charge was placed properly and was of the right amount. Note that none of the 
pieces were thrown far, though the stone is well broken up. 

16 



in a long, narrow mass — if there is a long depression, or crack, or the rock is much 
longer than it is broad. Thin edges of the mass should be pressed in and made 
steep and square. 

Before all of the charge is in place, put in the cap with fuse or the electric 
blasting cap. See pages 143 and 150. The best way is to prime a part of a 
cartridge of explosive in the usual way and bed this in the 
Inserting Cap loose explosives. If you decide to do this, stand the primed 
powder on end, with fuse or wires projecting from the top, 
and the closed end of cap pointing toward the center of the whole charge and 
then press the rest of the loose explosive about it. 

If a primer of this kind is not used, the cap must be inserted directly in 
the charge. To do this punch a hole a little larger round than the cap about 
one-third of the way down in the top of the charge. The cap should be in the 
upper third of the charge. To place the cap deep in the mass might lower the 
efficiency of the blast. 

Use the handle of the cap crimper or a blunt-pointed stick for punching 
the hole, as directed on page 147, and see that the cap is pushed to the bottom 
of the hole and that the explosive is pressed closely around it. 

The covering of mud should be put over the charge carefully. Be sure 
that the cap is not pulled out of the explosives during the covering operation, 
or later. 

The mud cap should be, preferably, of stiff wet clay. If clay cannot be 
got conveniently, use the heaviest earth you can find. 
The Mud Covering Sand is the least satisfactory material, but can be 
used if made thoroughly wet. In any case, the mud- 
cap must be MUD and not dust. 

At least 6 inches of mud cover should be placed over the explosive. This 
means 6 inches of covering in all directions over all of the charge. If the charge 
is 6 inches broad, then the mudcap would cover at least 18 inches of the rock, 
with the charge centered under it. To make a mudcap when the surrounding 
ground is dry, it is a good plan to gather and mix the mud in an old dishpan 
or box. Then to apply it on the rock simply turn the pan or box over at the 
right place and press the mud down so that no possible air spaces remain be- 
tween it and the explosive or the stone. Be careful that there are no stones 
in the mud covering. They fly like bullets when the charge is fired. 

The amount of explosive to use depends on the size and shape of rock and 

on its toughness and hardness. Below is a table which will serve to guide the 

blaster. These figures should be high enough to 

Amount of Explosive cover tough stones. Less explosive may be used 

for rocks that are easier to break. Rocks smaller 

than one cubic yard require more explosive than their size-proportion. 

Approximate Number of Pounds of Explosives Required for 
Mudcapping per Cubic Yard of Rock 

Sandstone, slate and similar soft or easily broken rock . 1 lb. 

Limestone and other intermediate rock 134 lb s - 

Marble, trap, granite and similar hard tough rock .... 2 lbs. 

While this table serves as a basis for calculating the amount of explosive 
required to break boulders, it is only approximate, as the weight of the charge 
does not continue to increase according to the number of cubic yards in the 
boulder. Some blasters may prefer the following table, which gives the approxi- 
mate number of cartridges required for each diameter of stone. 

17 



Number of H4 x 8 Inch Cartridges of Explosive Required for Mudcapping 
Boulders of Different Sizes 



Sandstone slate and similar soft, 
more easily broken rock 


Limestone and 
intermediate 


other 
rock 


Marble, granite, trap 
and hard, tough rock 


1^2 ft. 

2 " 

2L, " 

3 " 

I 


greatest 


dia. 134 cartridges 

" \% 

" 2 

" 4-5 


V/2 cartrid 

2 

V/2 " 
2K-3 " 
5-7 


ges 


23^ cartridges 
3 

3V., 
4 


5 " 


" 


" 7-10 









Charges in mudcap blasting may be fired by either 

Firing Charges fuse and caps or by the electric method. The advantages 

of each method are discussed on pages 159 to 164. The 

electric method is the only one that can be used when more than one charge 

is to be fired at the same time. 

The kind and grade of explosives best to use for mudcapping rocks is one 
having a very quick action of great shattering or disruptive power. The best 
explosive for this purpose is one of 40%, 50% or 60% strength. The straight 
nitroglycerin dynamites are a little quicker in action than 
Kind and Grade the " extra ' ' or ammonium nitrate explosives, and for mud- 
of Explosive capping should be the first choice. See page 1 53. But the 

ammonium nitrate dynamites are equally powerful, when 
of equal percentage strength, and though they are slower in action, tending to 
break the rock into larger pieces than nitroglycerin explosives, their work is 
satisfactory for mudcapping. 

When another explosive than those recommended above is on hand on 
account of some other use, it may be used for mudcapping with success, though 
its use may be more expensive. Almost any high explosive for farm, mine or 
quarry work, may be used in an emergency. Even the 20% high explosives 
that are best for soil blasting can be made to break rocks in this way, though their 
performance will not be very satisfactory. When these lower percentage ex- 
plosives are used, particularly if of the ammonium nitrate type, the quantity 
must be increased greatly. The use of such explosives will result in cracking 
the stones into a few large pieces rather than into many fragments. Whenever 
there is much mudcapping to do it will pay to get the proper explosive. In 
cold weather, use only the low freezing grades of these explosives. 

The only tools necessary for mudcapping are a shovel, a pocket- 
Tools knife and cap crimper, though an old dishpan or similar receptacle 
and a water pail often can be used to advantage. 

Breaking average sandstone boulders by blasting by the mudcap method on 
some jobs has cost fifteen to twenty cents per cubic yard. Granite, limestone, 
marble and trap rock boulders have been broken for slightly 
Cost and Time more. Mudcapping costs per cubic yard of rock run up 
fast when the boulders are very large, say larger than 6 to 
8 cubic yards each. Trap and other tough rocks are expensive to mudcap. 
The shape of the rocks has much to do with the cost and practicability of break- 
ing them in this way. 

The approximate cost of mudcapping can be computed on the basis of the 
amount of dynamite required as given in table on page 1 7. The time required 
to mudcap rocks is very little. When wet ground for the mudcap is at hand, 
a man can have a stone lying round in pieces within 1 or 15 minutes after he 

18 



gets on the ground. Many practiced blasters use no more than 5 minutes for 
each boulder. 

Three feet of fuse burns about a minute and a half and under ordinary 
conditions is enough to permit the firer to reach a place of safety. If an electric 
blasting machine is used, the operator should stand at least 
Suggestions 250 feet away, and should watch for and dodge any flying piece 
of rock coming in his direction. Avoid standing behind a shelter 
that may let stones through, as the branches of a tree. See page 164 for dis- 
cussion of misfires. 

A rock will often break better if it is jacked or pried from the ground and 
allowed to rest on small stones under the ends or corners. Sometimes odd shaped 
rocks, particularly if they are long, are broken better with two or more mudcap 
charges placed at different points and fired simultaneously by the electric 
method, than by one charge. Usually it will be best to locate such charges on 
opposite ends of the rock, though this rule is not good every time. Sometimes 
one may be a mudcap and the other a snakehole or undermine charge. Before 
proceeding with any mudcapping, read the chapter of this bulletin beginning 
on page 152, about the nature of explosives, detonation, tamping, freezing, 
thawing, etc. 

The result to be expected from a successful mudcap blast is to break the 
stone into a great many pieces, none of them too large to handle. If a heavy 
blast is used on a small brittle stone, half or more of the stone may be almost 
powdered, and few or none of the pieces may be much larger than a man's fist. 




B 






% 




i j~\ ffVjti 


ji^pAteiJ 


1 it iTiiif '^feraSPw^ 






5Hp %& 


Iplfjjsi 


j^S^Ww'.-r* 


^.j^PpE 




ueTSj^P^^^ 


- 


■v- : t\ 



Two pictures: How a proper undermine blast can be made to break a stone that is partly buried. Two charges of 
SO per cent, ammonia explosive were used under this stone, and fired simultaneously, with the result shown. 

Undermine or Snakehole Blasting 

To break a stone by the undermine blast method, the charge of explosive 

is placed against the under side or bottom of the stone with the solid ground 

as its backing. Less explosive is required than with a mudcap, 

Description since the confinement is better, owing to the earth backing and 

the weight of the stone. 

This method is superior to mudcapping because less depends on the shape 

of the stone under the ground or the depth it is buried, which are always hard 

to determine with certainty. 

19 



Undermining or snakeholing works better when the stone to be broken has 
a flat side down, and with flat boulders rather than round ones. 

To shatter a stone by this method, as by other methods, due attention 
must be given to the hardness, toughness and seams, 
Locating the Holes as outlined on pages 17 and 19. 

When a boulder is well buried the first thing to 
do is to probe about it with a sharp quarter-inch steel rod, to learn the shape 
of the under side and the condition of the ground. In any case, the charge of 
explosive should be placed as near as possible underneath the center of weight 
of the rock. 

Holes for the explosive can be made with a crowbar and sledge or with a 

dirt auger. The crowbar likely will be the most serviceable. If the hole is not 

large enough to hold all the explosive required at the right 

Making Holes point, you can make use of a scraper to enlarge the hole at 

the bottom. See page 61 for illustration. In blasting very 

large rocks, small tunnels can be shoveled out. 

The practice of enlarging the bottom of the hole by "springing" with an 
inch or so of a cartridge of explosive, is seldom to be recommended in undermine 
blasts of stones, on account of possibly enlarging the cavity too much and 
forming cracks extending into the surrounding earth. 

The explosive should be placed as nearly against the rock as possible. 
When the rock is undermined by digging, the explosive should be packed in a 
compact bulk, as in a mudcap charge. If you get the 
Placing the Charge charge an inch or two away from the rock with dirt 
between, its breaking effect on the rock will be re- 
duced. Read the directions for loading a hole, on page 28, and for placing a 
mudcap charge on a rock, page 16. 

The cartridge of powder containing the blasting cap should be the last or next 

to the last to go in. The cap should not be against the rock, 

Inserting Cap but if possible in the outside portion of the charge. The 

business end of the cap should be pointing directly toward 

the center of the charge. 

The charge must be thoroughly and tightly tamped. If there is not good 
firm resistance all the way round it will blow the dirt out from under the rock 
without doing any stone breaking at all. It is a good plan sometimes to tamp 
the dirt the whole way round the stone before the charge is exploded. Never 
use a metal tamping rod in the hole or near the charge of explosive. It may 
strike sparks from the rock or from small pieces of stone, and cause a premature 
explosion. 

Firing the charges may be done either by the cap and fuse method or with 
electric blasting caps and blasting machine. Each method has its advantages 
and adaptations to certain conditions as fully explained on pages 1 59 
Firing to 164. How to prepare charges, including the fixing of the fuse and 
cap, inserting and tying them in the cartridge of explosive and other de- 
tails, are told on pages 1 42 and 151. 

The amount of explosive required to shatter rocks by the undermining 

method depends on the size, shape, toughness and hardness of the rock. The 

table here will serve as a guide. These figures 

Amount of Explosive should be high enough for average tough rock, but 

it must be remembered that the amount of explosive 

required does not always change according to the size of the rock to be blasted. 

20 



Approximate Number of Pounds of Explosives Required for Shattering Boulders 
" Snakehole " by Undermine Blasting, per Cubic Yard of Rock 
Sandstone, slate and similar soft or more easily broken 

rock % lb- 
Limestone and other intermediate rock 1 lb. 

Marble, granite, trap and similar hard, tough rock \y lbs. 

Some blasters may prefer a table based on the diameter of the stones. 
Such a calculation can be used satisfactorily, but in this case, too, a great deal 
depends on the shape of the boulder. 

Approximate Number of X\± by S-inch Cartridges of Explosive Required to 
Shatter Boulders of Different Sizes by Undermine Blast 

Limestone 



and other Marble, granite, trap and 

tough rocks similar very hard, tough rock 
1J4 cartridges 2 cartridges 



2 
4-6 



2y 2 

3 

3^ 



Sandstone 
13^2 ft- greatest dia. 1 cartridge 

2 \H 

iy 2 " •■ '• \y 2 

3 " " VA 

4 » » «• 3 ^ 

5 " " " 6-7 
If larger sizes are to be broken, 

better calculate the amount of ex- 
plosives required by the cubic 
yard basis. Your figures will be 
more accurate. When rocks are 
to be rolled out without shatter- 
ing, comparatively small charges 
can be used. The following table 
will give an idea of the amount of 
explosive necessary. 

Approximate Quantity of Explosive 

Required to Roll Out Buried 

Boulders 

I 1 2 ft. dia y cartridge 

2y 2 " " h " 

3 " " 1 

4 " " \y 2 " 

5 '■ " 2 

Larger sizes than listed require 
proportionately increased charges. 
The extent to which the 
boulder is buried and the nature 
of the ground also influence the 
amount of explosive required. 

Probably the most economical explosive for breaking rock in this way is 
30% to 50% strength dynamite of either the nitroglycerin or ammonium ni- 
trate class. On account of the better confinement secured 
in this method, stones can be broken more effectively and 
successfully with slower and less powerful explosives than 
by mudcapping. 20'; to 40% strength dynamite often 
21 




A striking illustration of the action of a proper under- 
mine blast. The rock is lifted a few feet and cracked, 
but is not thrown far. Look closely and you can see 
the cracks where they had begun to form at the instant 
the picture was made. 



Kind and Grade 
of Explosive 



will prove satisfactory. Any standard strength of nitroglycerin, ammonium 
nitrate or gelatin dynamite will do the work. 

To roll stones out without breaking them, the high percentage explosives 
can be used successfully, but they are not as well suited to the purpose as the 
slower ones, such as 20% ammonium nitrate dynamite. If you are buying 
explosives for breaking rocks, however, buy those best suited to the actual 
breaking, and do the rolling out of the stones with the same explosive. 

The tools needed in snakehole or undermine blasting of boulders are the 
testing rod or probe already mentioned, a shovel for handling dirt, a crowbar 
or dirt auger, a wood tamping rod 13<£ inches in diameter, and a cap 
Tools crimper. Several other items in the tool list can be made use of to 
good advantage where there are many stones to undermine. One is a 
3-inch fence post, to tamp the ground tight about the edges of the stone. Another 
is the scraper, for enlarging the bottom of an auger hole. 

Undermine or "snakehole" blasting is a slightly cheaper method than 
mudcapping when conditions are favorable. It is often found that the cost per 
cubic yard increases with stones smaller than one cubic yard, and is very much 
less with stones containing several cubic yards. Sandstone 
Cost and Time has cost ten to fifteen cents per cubic yard to break in this 
way, and the other kinds in proportion. This is one of the 
most serviceable and satisfactory methods of blasting boulders. The cost can 
be calculated by referring to table on page 21. Add labor cost to the total for 
explosives. Sandstone and other such easily broken material can be broken up 
cheaply, while marble and trap come higher. Although the cost of explosives 
is somewhat less than with the mudcap method, this is partly offset by the 
additional labor required in making the holes in the ground. Ordinarily a man 
can make a hole and place a charge under a stone in 1 5 to 20 minutes. 

Combinations of snakeholing and mudcapping sometimes are effective 
with stones that lie on the surface of the ground or are imbedded only a little. 




POORrAAtP/NC 

-fvsec : '- 






'DANGEROUSLY JAMMED 
^p/Rt&ETWEEA/Sr/C/fJ Of POWDER 
'AIRSPACES'""- ' " - ;"7 " 



A combination of evils. Such loading could not result in breaking a boulder. Note the seven faults. 

22 



To make use of the advantages of such a combination an elec- 
Suggestions trie blasting machine to produce simultaneous exploding is nec- 
essary. It is not wise to attempt the combination of top and 
under shots when a stone is buried deeply Better roll it out first. 

Two points of caution are desirable. Beware of misfires. See page 164. 
Remember that snakehole or undermine blasting may throw pieces of rock 
with considerable force and range, but the danger can be reduced 
Cautions to a minimum if proper precautions are taken to see that every 
person and animal is out of range of flying rock and fragments. 
It is not unusual in snakehole or undermine blasting to see pieces of stone 
thrown more than 100 yards. 

Blockholing 

This method of breaking rock with explosives consists in drilling a hole 
into the boulder, putting the explosive at the bottom, tamping tightly, and 
firing in the usual way. It is remarkable how small a charge of explosive will 
break a big boulder, even of the hardest and toughest kind, when placed in 
this way. One cartridge of explosive in a drill hole 1 8 or 20 inches deep in a rock 
will do more damage than several cartridges on the surface. 

The blockhole method of blasting is the best way of break- 
Description ing large, tough boulders that are not too hard to drill and 
which do not break well from a surface blast. 
Drilling and blasting in a similar way is nearly always the only practicable 
method of blasting ledge rock. 

The nature of the rock has a good deal to do with the point at which it is 
best to place the explosive. Ordinarily it will be found that the charge should 

be located somewhere near the center of the 
Character of Rock and boulder, though different kinds of rock require 
Placing of Explosives different depths of holes. A brittle rock which 

does not split well and a tough rock such as trap, 
must be drilled deep in order to break it right, while a shallow hole will give 
satisfactory results in a rock which is easy to split, or which crumbles apart 
like slate. 

A rule that may be applied to all rock is that the deeper the drill-hole, 
down to 3^2 or 3 5 the way through the rock, the less explosive will be required, 
and the greater will be the execution of the blast. In boulders that are very 
hard, and so big that they require a large charge, it once in a while pays to drill 
a very small hole, and then spring this hole at the bottom by exploding at that 
point a small charge of explosive, using no tamping. Such a practice will be 
needed rarely in boulder blasting, though it is often useful in blasting out ledges. 
Holes may be drilled by one man alone, or by two or 
Drilling Facts more men. One-man drilling usually is the cheapest when 
holes are made by hand. The drilling can be done with 
ordinary hand hammer drills, with churn drills (finishing deep holes), or with 
machine drills. 

A hand drill is just a straight piece of drill steel, which is medium hard 
and very tough, with one end shaped into a proper cutting bit. This bit is } 3 
to \'2 or more wider than the shank of the drill, with the 
Hammer Drills cutting edge somewhat rounded up to the corners and 
sharpened in the form of a "v," the angle of which should 
be long and thin or short and thick, according to the kind of rock to be drilled. 
In soft rock use a long thin cutting edge; in hard rock a short, thick edge # 

23 



You can buy drills of different lengths and diameters from mine supply 
houses or hardware dealers anywhere. & Or you can buy the steel from hard- 
ware stores and make them. Drill steel comes in 5 g-inch, >g-inch and other 
diameters, in bars up to 20 feet long. If you plan to make your own drills, be 
sure to have on hand a good length of it, for even if you have only a dozen 
boulders to blast you will need several drills as they require sharpening fre- 
quently. 

If one man is to do the drilling, the hand hammer should weigh 3 or 4 
pounds; if two men, 8-pound sledges are about right. All hammers should, of 
course, be flat faced. The drill should be turned about }/g of a revolution at 
each stroke of the hammer so as to keep the hole round. The more regularly 
this is done the nearer true the holes will be and the faster the bit will cut. 
The holes can be started with a short drill — say 8 or 10 inches long — easier than 
with a long drill. 

The right diameter for a hole in a boulder usually will be about one inch. 
It is well to keep the hole as small as possible, for it takes a good deal longer 
to drill a big hole than a small one. For instance, it takes 
Size of Holes about four times as long to drill a 2-inch hole as one an inch 
in diameter. If the 1 -inch hole will contain enough explosive 
it should be the size selected. But it must be remembered that as the hole 
goes down, the ears of the drill bit will wear off and the hole will grow smaller, 
so that in hard rock it is well to start a hole that is to go deeper than a foot or 
so, with a drill J4 inch larger than is wanted at the bottom. In boulders con- 
taining more than 6 or 8 cubic yards of material it is best to drill inch or inch 
and a quarter holes. 

The holes should be kept wet by pouring in water as the drill goes down. 
In this condition, the drill cuts much faster than in dry holes. It is necessary 
to keep the holes clean. The sludge, as the ground-up rock is called when 
mixed with water, can be taken out with a scraper which is shaped somewhat 
like a very small garden hoe, or with a spoon rod, which is a small wood rod 
with a disc of tin on each end. The discs should be of different sizes, and at 




Pressing in the tamping after a charge of explosive has been seated in the bottom of a blockhole 

24 



one point they should be cut to the center and one of the cut edges bent down, 
so that when the rod is revolved in the bottom of the hole the edge will scoop 
up some of the sludge. 

Another good way of cleaning out holes is to use a spiral hook, or drag 
twist, like an old-fashioned rifle cleaner. Rags or hay can be used on this to 
wipe the hole. A hickory or willow stick with the end split into many small 
pieces, or broomed, is also a good thing for getting dirt out. When this is dipped 
in the sludge, the material sticks to it, and can be lifted out and knocked off 
against the outside of the stone. 

A leather or rubber washer, or some old rags, should be fixed round the 
drill just above the level of the stone, to prevent the sludge and dust from fly- 
ing up into the face of the driller. This is particularly necessary when churn 
drilling. 

A churn drill is a piece of drill steel from 5 to 6 feet long, often having bits 
at both ends. It is used without a hammer — a man raises and drops it into 
the hole. Holes cannot well be started with it. It will cut 
Churn Drills holes faster than a hammer drill under favorable conditions, 
but owing to the way it is worked its use should not be at- 
tempted in holes less than 6 or 8 inches deep. For deep holes and in soft rock 
it certainly should be considered. A good churn drill for 1 -inch holes should 
weigh about 10 pounds. 

Bits should be kept sharp, for dull drills do only a fraction of the work 
they should. To sharpen bits costs about five cents each. It may be done in 
a blacksmith shop or, in emergencies, with a file or on an emery-wheel or grind- 
stone. They should be made as sharp and hard as 
Sharpening Drill Bits they can be used in the rock to be drilled without 
either dulling too fast or chipping. The angle of 
bevel that is best generally will be about 90 degrees for hard rock and 45 to 60 
degrees for soft rock. Your blacksmith will give you the proper kind of bevel 
if you give him the necessary information. Good drill steel is not tool steel. 

Before attempting to sharpen a drill the shape of a new bit should be 
observed. Heat the drills to cherry red, and do not hold them long at that 
temperature. Work to get them hot without delay, then take them out of the 
fire promptly for dressing. 

The bit should be hammered to shape on the anvil, with the shank of the 
drill held so that it has 1 foot rise to 2 feet of length. You likely can use a file 
to advantage to help shape the edge, while the steel is hot. When the bit is 
shaped, it is ready to be put back into the fire and reheated for tempering. 

The tempering should be started when the steel is at a temperature of 430 
degrees F. You can tell the temperature by the shade of the surface or color 

film that forms on the surface as the steel is being heated. 
Tempering Drills When the bit has been heated slowly until the surface 

has nearly a cherry red shade, take it from the fire and 
hold it in the air till it gets a very pale yellow. Rub it on a stone to remove 
the scales so the color can be seen unmistakably. If it seems to take too long 
to reach this color in the air, plunge it into the water and out again at once to 
start the cooling. Then watch the colors by standing in a dark corner. They 
should advance parallel to the edge. If they don't, hold the hot corner or side 
in the water an instant to even up the entire bit. As soon as the very pale 
yellow color is noticed, stick the bit into cool water and leave it there, stirring 
it about till most of the heat has left the steel. 

25 



Temperatures of the steel that are indicated by the colors are as follows: 

Very pale yellow 430 degrees F. 

Straw color 470 

Brown 490 

Purple 530 

Full Blue 560 

Dark Blue 600 

Cherry Red 900 




How a proper blockhole blast will shatter a boulder into pieces of all sizes. Note how completely 
the stone is broken throughout its entire volume and not just at one side or corner. 



The time in which two men with hand drills can make holes in rock can be 
told best by stating the number of minutes it takes per inch of hole in different 
kinds of rock. For beginners, when two men are drilling holes an inch in di- 
ameter in rock such as sandstone, about 2j^ to 3 minutes per inch in depth is 
required; in limestone 3 to 3]/9, minutes; in granite 4 
Time for Drilling minutes; in mica schist 5 minutes; in marble and trap 
rock 6 to 8 minutes. Single hand drilling (one man) 
proceeds about two-thirds as fast, except that in soft rock the rate is upwards of 
three-fourths as fast and in very hard rock only half as fast. These figures 
change greatly according to the experience of the workers and the condition of 
the sandstone, limestone, granite, schist, marble or trap rock that is drilled. 
Machine drilling is very much faster than hand drilling, and much cheaper 
where there is enough drilling to do to justify the pur- 
Machine Drilling chase of an outfit. Since there are many owners of large 
acreage which requires clearing, also many contractors in 
stump and stone removing who will use this handbook, some of the data about 
machine drilling will be useful. 

26 



In clear rock, or rock not checked, machine drilling is 5 to 1 5 times as fast 
as hand drilling. In some sandstone it is possible to go down at the rate of a 
foot in 5 minutes (instead of an inch or two as in hand drilling); and 
Speed in trap rock at the rate of a foot in 10 or 12 minutes. In limestone 
the rate is even faster than in some blue sandstone, there being records 
of instances where a foot has been drilled in 3 minutes. Hard granite and flinty 
rock often drills at the rate of a foot in about 7 minutes. 

Blockhole blasting is more economical than undermining, the cost depend- 
ing partly on how difficult the rock is to drill. Blockholing requires a 
Cost smaller amount of explosive and larger amount of labor and time than 
• mudcapping or "snakeholing." 
The cost of machine drilling usually is much lower than of hand drilling — 
often it is about one-fourth or one-third, of course not including depreciation 
or interest on the cost of the outfit. This is much or little per foot of hole 
drilled, according to how steadily the outfit is used. It may amount to only a 
fraction of a cent, or it may run the total cost up higher than that of hand 
drilling. 




How a boulder can be broken into pieces small enough to handle easily without shattering it into 
fragments, with proper charges of 20 per cent, ammonia explosive placed in a blockhole, or by 40 per 
cent, explosive used as a mudcap. This stone shows by its breaking how joint and bed lines run. 



There are two types of machine drills operated by steam or 

Machines compressed air— the small jack hammer type and the large tripod 

drill. The jack hammer drill is the best type of machine for use on 

boulders. Jack drills are portable and easily handled. Tripod drills are heavy. 

The tools needed in blockhole blasting, aside from drills 

Other Tools and hammers, are a pocket knife for cutting fuse or scraping 

wires, a cap crimper and a wood rod for tamping. Crowbars 

are often useful. 

27 



Kinds and Grades 
of Explosives 



The kinds and grades of explosives that can be used for blockhole blasting 
are many. In fact, rock can be broken by this method with almost any blast- 
ing explosive. But certain facts should be understood by blasters. One is 
that the use of a high strength quick-acting explosive, 
such as 50% or 60% dynamite will shatter rock into 
small pieces, while the use of slower explosives such as 
20% strength will crack and split it into larger pieces. 
Ammonium nitrate dynamites are considered somewhat superior to nitro- 
glycerin explosives for this purpose. For the ordinary breaking of boulders 
into pieces small enough to handle easily, there is nothing better than 20% to 
40% ammonium nitrate dynamite. 

In blasting in quarries, 5 tons of rock often are brought down per one 
pound of explosive. It is difficult to maintain this 
ratio in the field, unless it be with very large rocks, or 
ledges with an open or free face. Small boulders 
often require more explosives per cubic yard than 
large ones. The shape of the boulder is also an important point, so the follow- 
ing tables can only be considered as approximate. 



Amount of 
Explosive Required 



Approximate Number of Pounds of Explosives Required 

to Break Boulders by the Blockhole Method, 

per Cubic Yard of Rock 

Sandstone and other more easily broken rock M lb- 
Limestone and other medium rock Y% lb. 

Marble, trap and similar hard, tough rock x /i lb. 

Figuring on the basis of the diameter of the stones and the number of 
cartridges of explosives required, the tabulation is: 

Approximate Number of Cartridges of Explosive Required to 
Break Boulders of Different Diameters 

Sandstone, Slate and Limestone and 

similar easily broken other medium 

rock rock 



\y 2 ft. dia. 

2 " 

2K" 

3 " 

4 " 

5 " 
7 " 



*4 cartridge 



\ X A 
6 



}^-y'S cartridge 



2 



Marble, Granite, Trap, 

and similar hard, 

tough rocks 

}/2 cartridge 
\A 



2 

3 

10 



Often from experience, an observant man will learn just how much ex- 
plosive is required to crack a stone and lay it apart without excessive throwing 
of pieces, danger and waste of explosives. 

All water should be wiped out of the holes. If the holes are smaller than the 
cartridges of explosive the paper wrapping of the sticks will have to be removed 
and the explosive pressed into the hole so that there are 
Loading Charges no air spaces. The cap should be placed in the charge 
near the top. Tamping of damp or wet clay or other 
earth should be placed solidly over the explosive to the mouth of the hole. 
Results of the blast with the smallest charges will be poor unless there is at 
least 6 or 7 inches over the powder. 

28 




An undermine blast that was too heavy was used here to break a very hard, tough boulder. As 
a consequence the rock is broken only into large pieces and these are thrown long distances. A better 
way would have been to have used a very heavy mudcap blast on top of the rock, or, still better, a 
proper blockhole blast. 



The firing of blockhole charges may be done either with fuse and cap or 

by the electric method. If more than one charge is to be fired, the 

Firing electric method will enable you to put them all off at once. Electric 

firing is of much advantage in blasting out ledges, and also in firing 

the very small charges sometimes used to break stone to certain dimensions. 

Sometimes what may be called a " semi-mudcap " blast can be used in 

very hard stone, or in stones that are difficult to drill. Drill a hole into the 

stone for 3 to 8 inches, fill with explosive, let the rest of the charge of explosive 

pile up on top of the rock as you would a mudcap charge, in a low cone with 

steep edges. Cover this with 6 inches or more of wet clay. 

Boulders that are buried may be thrown out of the ground before they 

are blockhole blasted. When the earth is supporting them on 

Suggestions all sides they may not break quite as well. Digging round 

them or raising them off the ground with a jack or pry, and 

letting them rest on small stones placed under the ends or corners, helps to 

break them up better. 

Blasting in drilled holes is practically the only method that is effective in 
breaking up ledges of rock, either underground or above the surface. Drill a 
line of holes along back of the edge or face of the ledge 
Breaking Ledges above the surface. It is not necessary to dig or blast 
away the dirt from a ledge. The quantity of explosive 
required can be gauged by the table giving the amount to use per cubic yard 
of rock. Use half again as much explosive in a ledge blast as in a boulder. 
Measure the distance from the open side or face of the ledge back to the drill 
holes, and compute the number of cubic yards that should be broken off. 

Ordinarily on farms or in roads it is desirable to break up ledges to a depth 
of about 2 feet below the surface. To do this the holes should be put down 
slightly more than 2 feet and should be located 2 or 3 feet back from the face 
of the ledge. To break ledges deeper, drill deeper holes farther back from the 

29 



face and charge heavier. The deeper holes can also be farther apart. Two- 
foot holes usually can be 5 feet apart in soft, brittle shale and slate, 4 feet apart 
in limestone, and 3 feet apart in harder material. The spacing between the holes 
should be about the same as their distance back from the face. The details of 
charging holes, drilling, tamping, firing, etc., that have been given for boulder 
blasting apply equally to ledge blasting. 

Blockhole blasting is perhaps the most efficient method of breaking rock 
that is known, and from it you can expect perfect results. If you use a proper 

charge of a quick explosive, the rock will be shattered 
Results to Expect into small pieces. If you use a slow explosive, the rock 

will be broken into larger pieces. In any case, the use 
of the charges recommended here will result in the satisfactory breaking up of 
any rocks you may have to deal with. 




How boulders are shattered into fine pieces by heavy mudcap charges of 60 per cent, nitroglycerin 
explosive. Note the amount of stone that is so small it will not need to be hauled away. 



General Considerations 

The information on boulder blasting, and particularly on the breaking of 

ledges of rock, applies to quarrying limestone or road material, gravel, etc. 

In quarrying, it is better to drill larger holes than one inch. 

Quarrying Proper loading in inch and a half holes, drilled to depths of 6 or 

8 feet, and 5 or 6 feet back from the edge of the quarry ledge will 

loosen large quantities of rock. 

It does not pay to dig hard-set gravel or sand by hand, for in such material 
the holes are easy to drill, and comparatively small charges of explosive will 
loosen great quantities. For quarrying use 40% ammonium nitrate explosive 
unless the rock is wanted in large pieces, when 20% ammonium nitrate grades 
will be better. For the semi-rock, hard gravel, etc., use 20% explosive, the 
granular powder known on the market as R.R.P., or if the work is dry, black 
blasting powder. 

30 



Emphasis should be placed on the possibility of using explosives as a labor 
substitute. To illustrate, take the disposal of a 4-foot sandstone boulder. To 
drill this with an inch hole 32 inches deep would require about V/% hours, or 
slightly less, for two men. But one man can smash the same boulder within 
10 minutes by placing a proper mudcap blast. In the 
Explosives as a first case the breaking of the boulder is achieved with 
Labor Substitute greatest economy in total outlay, but in the latter case 
it is broken by one man, and broken without interfering 
seriously with other work. On many farms there is so much to do and men are 
so scarce that to take the 1}^ hours for the boulder's removal is out of the 
question, and the boulder remains in the field — unless it can be broken up with 
little labor and loss of time. 

When a boulder that is nearly all buried is rolled out and blasted, there 

likely will be room in the hole for many of the large pieces, deep enough to put 

them all below the plow line, but it is not well to bury 

Disposal of Pieces pieces larger than 6 inches in diameter, as the broken 

rock will be valuable for building purposes, for road 

making, lining ditches, etc., and should be kept in the stone pile until needed. 

It costs about 35 cents a cubic yard to haul pieces of stone away, figuring 

on the average haul. Solid rock of average density weighs about 2 tons to the 

cubic yard and loose material as it falls weighs about 1 1 3 tons to the cubic 

yard. It is better to put a stone rack on a wagon if a wagon is used. 

Hauling Such a rack can be made of 2 or 3 inch plank. To get heavy pieces 

of stone on the wagon, use planks to skid or roll them up. If the 

pieces are very heavy, use a "stoneboat" instead of a wagon. It is better for 

short hauls because it saves so much lifting. An average load of stone is about 

a ton and a half, and two men will handle this in about half an hour, including 

loading and unloading. 

The holes from which boulders have been taken should be filled level, to 
avoid a low place in which water will gather during wet weather. To fill the 
depressions, a horse drag scoop such as is used in excavating 
Filling Holes dirt is a useful thing. If this is not available, a good thing to 
use is an ordinary road drag, or a split log. By standing on 
the drag or log it can be made to gather a lot of ground, and the dumping can 
be done by taking off or shifting your weight. 

In addition to various tools described under the separate headings on 
methods, blasters of boulders will find a heavy crowbar and an iron wedge to 
be useful at times for prying apart pieces of rock. Some blasts will be found 



G 



Steel bar for making 
holes. 



Soil auger — note __ , , „ „^,. , 



long point. 



not quite heavy enough to throw the stones apart, 
Tools and Appliances though they will crack the rocks through and 

through. These stones can be reduced with a sledge, 
but a little prying will accomplish more than a whole lot of hard hammering. 
If the bar cannot be forced into the crack use the wedge and sledge it in. Be 
careful that the wedge does not strike solid rock at a bed or joint line running 
at right angles. The wedge should be a slim piece of tough steel, 6 inches long 
and an inch or two thick at the base. 



The best tamping material is damp clay. Tamp the hole full, while working 
in the tamping with the stick in one hand, hold the fuse or the electric wires 
out of the way with the other hand. It is easy to damage fuse 
Tamping and wires by breaking the insulation with a pebble, or with the 
edge of the tamping rod. It is also easy to pull the cap out of the 
primer charge unless the fuse or wires are held firmly against the rock. Many 
misfires are due to carelessness at this point. 

In lighting a fuse, stick the flaring head of a burning match right against 
the powder in the end. See page 1 59. This will work in any wind. The fuse 
always gives a pronounced spit as soon as it is lighted. Do not leave before the 
sparks and smoke begin to spit out regularly. 

It may be safe to stand 100 to 150 yards away from a blast that is not 
overloaded, but this is a matter which each blaster will have to decide for 
himself. Much depends on the proportion of the charge to the boulder, its 
location, and whether the stone is solid. The right charge 
Flying Pieces will not throw stone far, but a charge that is too heavy, 
or in the wrong place, will throw large pieces for long 
distances. In fact, this is one of the ways in which you can tell whether or not 
you are using too much explosive. In any case, to be safe, keep an eye on the 
blast and dodge any flying fragments coming your way. 

Use every care to keep everybody beyond the range of danger. The man 
who fires the charge should keep his eyes open for stones coming down several 
seconds after the blast and at distances 1 00 yards or farther away. 

They are dangerous. See page 164 for discussion of 
Watch Misfires their cause and remedy. 




How a large granite sandstone or limestone boulder can be shattered with a mudcap blast. At 
the point next the explosive the stone is broken into small fragments, but at the other side it is left 
in large pieces, though it is well cracked in every direction. 



32 



CLEARING LAND OF STUMPS 
To Clear or not to Clear 

A "stump" may be denned as any kind of a growth that obstructs land, 
whether it is the butt of a cut tree, a tall snag, a living tree or a bunch 
of sprouts or brush. From the viewpoint of a farmer it is a stump if it ob- 
structs the plowing and other tillage of the land. 




The sort of wreckage practically perfect stump blasting should give. The pieces are shattered so they 
are easy to handle and so they burn well. 

Before deciding to clear land, the owner should consider several features 

of the matter well. The reckless slaughtering of the timber has left in stumps 

many thousands of acres of land which is not fit for 

cultivation and that should go back into timber. 

When Not to Clear Such land, of course, should not be cleared. On the 

other hand it is folly to permit brush land which has 

good soil to lie idle when a hundred years will not 

develop profitable timber on it. 

Much land that is in woods now should be left so, for timber and for fuel. 
Every farm should have its timber tract, where the forest is conserved in a 
way to make it permanent. To cut young growth that will make good timber 
in a reasonable time is a mistake, no matter how good the soil is. Remember, 
too, the wind-break value of a piece of woods adjoining farm land, and consider 
the effect on land you now farm of taking away the protection afforded. 

Do not clear land where the soil is too stony to be cultivated to advan- 
tage, or land that is exceptionally steep or incurably swampy. Do not clear 
when the profits would not justify the clearing. And do not clear when you 
can buy equally good improved land for less than the cost of clearing. 

There is a certain sentimental satisfaction in clearing and cleaning up 
one's own place, connecting fields and improving it generally, even though 
such improving will not add greatly to the actual money income from the 
crops. This will have a bearing in some instances. 

But hard-headed judgment should not be swayed too much by sentiment, 
for there are a good many thousands of acres that have been cleared and now 
are parts of farms, which it would be wise and profitable to plant to 

33 



forest again. Lay out your clearing carefully. Include no corners, gullies or 
steep places you will afterwards neglect. And make sure your field is rightly 
placed in relation to the rest of the farm. 




A fertile looking field which could not possibly pay a net profit of more than half what it should 
so long as the stumps remain as they are. Two or three years' gain in crops, or less, would pay for 
the blasting out of the stumps. 

About new clearing there may be some question, but about taking out 
stumps in good cultivated land there can be none. There are stumps in fields 
and along fences, roads, hedges and on home grounds. There are pastures 
that are pastures and not wheat fields or orchards because cultivation among 
the stumps is too inconvenient. There are old fruit trees and old shade trees 
that are diseased and a menace. All these should come out, and the quicker 
they come out the better. 




Worth little even as pasture land, never rising in value, but potentially worth $100 an acre as soon as 
it is cleared. This is the sort of valley floor that makes splendid fields of oats, corn, alfalfa and other hay. 

34 



The Profit and Loss Account of Stumps 

The man who is taking up the farming of cut-over land knows that he 
cannot do much until the stumps are removed. But lest he be tempted to 
permit some of them to remain in the cultivated fields, as many men on older 
farms are doing, it is well to point out some of the losses which stumps cause 
and some of the gain which their removal brings. 

No farm is well ordered when its fields are foul, and no farmer commands 
the respect of his neighbors when stumps are crowding out 
his crops. The loss in self-respect probably is even more 
Appearance serious. 

In farming stumpy fields a man does not have that sense 

of having done his best, which is half the battle for success. 

Tool breakage is another source of loss caused by stumps. Plows and 

furrows are broken, mowing machines and binders are both broken and racked 

and in some cases the use of machinery is prevented. Heavy engine tools 

cannot be used at all where there are roots in the ground. 

Greater speed and ease of cultivation is a prime reason for taking out 
stumps. The use of gang plows, wide harrows and other modern labor- and 




When the stumps are as thick as the hay piles or the shocks of wheat or oats or corn there is some- 
thing the matter with the farm system. They are boarders who never pay any bills. 

time-saving equipment and methods is practical and economical only on land 
that is clean, both above and below the surface. And such use is becoming 
of more and more importance, as farm wages go higher and labor becomes 
scarcer. 

The injury to horses often is much greater from a money standpoint. 
Spavins and sprains result from jerks against roots. Mares are caused to slink 
foals, young horses are made balky. The danger of injury to men is by no 
means absent. The kick of plow handles rupture many men, and every year 
sees its quota of broken arms and legs among farmers who try to plow, culti- 
vate or mow among stumps. 

Weed spread is a thing that must be charged up to stumps. They grow 
about the stumps, mature seed and pollute the whole farm. 

35 



Just as the presence of stumps tends to lower the value of land and to 
keep it down, clearing off the stumps will raise it and keep it 
on the increase. Once start to clearing away the stumps on 
Increased your place and the neighbors and people who pass on the roads 
Production will take it for granted that the place is a paying proposition, 
worth developing. If you want to sell it, there is no surer way 
of adding a few hundred or a few thousand dollars to the sell- 
ing price. To hold stump land for increase in value is a mistake. Clear it up 
and force the increase. 

The actual gain in crops to be secured by the removal of stumps can be 
measured by the proportion of the total ground that they occupy. For 
instance, in many cases a stump takes up a square rod of ground. In meas- 
uring the value of the removal of stumps, the gain in crops and in speed and 
ease of working the ground should be compared, not with the total value of 
the crop, but with the net profit before stumps are removed. Thus, if a 




This is the typical appearance of much land that is very fertile and which would 
pay handsomely if in alfalfa or fruit. (Near Linville Falls, N. C.) 

25-bushel crop of wheat costs 20 bushels to grow, the addition of 5 
bushels to the yield will increase the net profit 100 per cent. Two dozen 
stumps to the acre may occupy such a large part of the acre that their 
removal will double the net profit. 

The clearing up of land can be made to mean something more than the 
financial profit it brings, for when properly handled it well can be made one 
of the links that hold the boys to the farm. Once a boy has helped to develop 
a property in a way that he enjoys he will remember that place as home as 
long as he lives. And boys will be enthusiastic over the clearing operations, 
with the necessary planning for new fields, the blasting and stump pulling, 
and the burning afterwards, if the work is managed along some of the newer 
lines which take out the drudgery. 

The Essentials of Good Stump Removing 

Before settling on a plan for removing stumps, it is well to have clearly 
before you just what is required. 

36 



The stumps must come out entirely, or at least deep enough so that roots 
never will catch plows or other implements. Stumps with roots must be dis- 
posed of as profitably as possible, used if possible, or burned cheaply. They 
often can be sold or used at home for firewood of some kind, or sold for extract 




When all the trees of a wood-lot are cut down, the ground seldom is protected from animals and 
so treated as to grow a new piece of forest. But it should either be put in forest or cleaned up and 
farmed. The green stumps should be let stand a season, then should be blasted out with about four 
charges each. They are almost impossible to pull economically. 



purposes. Failing this, they must be burned on the ground with as little dam- 
age to the soil as possible. In any case they must be broken into pieces small 
enough to handle by hand, unless derricks and power are to be used to handle 
them. 

The total money expense of the clearing project must be within the capi- 
tal available for the purpose, and the labor and time required must not exceed 
the supply. The condition in which the ground is left also is important. The 
holes should be shallow, and the less littering and tearing up of the surface 
there is, the better. The work usually should be finished in time for planting 
a crop in the spring, for the loss of a year's time costs money. 

These are the things which should be included in the plans for clearing. 

Nature of Stumps and Conditions Affecting 
Their Removal 

There are about 500 different varieties of trees which make stumps in 
America, and it is not advisable to classify them all in this bulletin. What 
is of value is to review the nature of their roots. 

There are three general types of roots — lateral roots, semi-tap roots and 
tap roots. (See cuts, pages 53 to 55.) - Some varieties of trees always grow in 
one way; other varieties grow in either of two ways, depending on soil condi- 
tions. The stumps of some trees rot fast, while others are very durable. Some 
roots die when the trees are cut; others throw up sprouts. The wood of some 
roots is tough and can be twisted a great deal without breaking ; of other varieties 
it is brittle and will break off when bent or jerked. 

37 



Typical tap-root stumps are long-leaf southern pine, hickory and black 
gum. Some of these trees grow a root that is almost as big as the trunk, ex- 
tending straight down into the ground. Others have slender 
roots. Sometimes these tap-roots send out lateral roots of 
Root Growth some size, but in other cases the laterals are limited to hun- 
dreds of short, hair-like rootlets growing from the main tap- 
root. The tap-root itself sometimes splits at a point several 
feet underground into several smaller roots, all of them continuing to grow 
nearly straight down. 

Typical lateral root stumps are elms, soft maples, locust, dogwood, elder, 
hemlock and some cypress. The roots of these trees grow in all directions from 
the trunk near the surface of the ground. Working the ground close about such 
stumps is next to impossible. 

The largest class of stumps is the semi-tap-root class. Belonging to this 
class are white pine, poplar, chestnut, ash, walnut, red, black, pin and other 
oaks, persimmon and sassafras. Stumps of this class are harder to remove 




Wonderfully productive meadows, for timothy, alfalfa or other grass, can be made by cleaning up 
and draining stump flats. This land was a tangle of old logs and stumps a few months before the pic- 
ture was taken. (Michigan Land & Lumber Company.) 

than either of the other two types, because the roots generally are big and 
strong and grow in all directions, some along the surface, others almost straight 
down and still others between. 

What may be classed as a fourth division is composed of the root clusters 
of sprouts and bushes of almost any sort of trees, whose growth has not yet 
taken the characteristic form. Brush of willow, elder, maple, chestnut, hick- 
ory, oak and witchhazel may be named. The roots are very firmly anchored 
in the ground for a distance of three or four feet in all directions. 

The nature of the soil and the height of the water-table in it have much 
to do with determining the root growth. A hemlock tree, for instance, 
will send its roots down till they almost take on the nature of the semi-tap- 
root class in soil that is loose, free from stones and dry. The same tree would 
have few roots deeper in the ground than 6 inches where the soil is hard and 
the water-table near the surface. The root growth of other varieties of trees 

38 



is affected by water and soil in the same way. A tree that grows on a steep 
hillside probably will have heavier roots on the sides than on the downhill 
and uphill grades. 




A glimpse of primeval forest and of primeval stumps, the like of which few farmers meet in 
the eastern part of the country any more. Such land is expensive to clear but it is exceptionally fertile 
in most cases. 



Some stumps are durable and others will rot very fast. White pine, 
Norway pine, locust and cedar stumps will last fifty years without 
decaying enough to make much difference in the work of their 
Rotting removal. Chestnut, white oak and catalpa are nearly as durable. 
The other oaks, poplar, ash, hemlock, hickory and gum rot so 
fast that in a few years a team of horses can roll out stumps of 
considerable size. 

It should be understood that during the first season, after any variety of 
tree is cut and the stump and roots die, the bark and soft outer layer of wood 
rots away, making the roots loose in their earth channels. It is the inner or 
mature wood which lasts. 

Another characteristic of stumps which is of importance in clearing plans 

is their sprouting. None of the pine stumps will sprout when 

a tree is cut, but nearly all the hardwood stumps will do so. 

Sprouting Chestnut is a great sprouter. A stump that does not sprout is 

not getting any worse as time passes, but one that does sprout 

is likely to be harder to take out each succeeding season. 

All kinds of stumps pull easier when the ground is wet than when dry. 

Explosives are more efficient in wet ground than in dry. Pulling 

machinery ordinarily is handicapped in very wet ground, because 

Water of the lack of firm footing. 

The nature of the soil, whether light or heavy, has a consider- 
able effect on the way stumps come out of the ground. Naturally 
a loose, fluffy sand will hold the roots less than heavy clay. Pulling them out 

39 




This clump of trees was blasted out (not cut down). The stumps are torn out better than 
they might have been without the weight of the tops ta pull them over. 



of sand, therefore, is much easier than out of heavy soil. On the other hand, 
light soil will not confine the gases of explosives nearly as well as clay. In 
sand the greater ease of tearing the roots loose is more than 
Kinds of Soil offset by the lowered efficiency of the blast. 

The foregoing principles should be of more actual ser- 
vice to land clearers than a description of the conditions in different sections. 
If your stumps are Southern long-leaf pine, you know they will not sprout, 
and are of the tap-root class. If they are white pine of Michigan or Maine, you 
know they are of the semi-tap-root class, that they will not sprout and that they 




This picture shows what they look like when down. The roots are torn out better than they would 
have been without the tops to pull them over. Note how easily they can be sawed or chopped. 

40 




When stumps are lifted by frost as much as some of these, they cften can be pulled economically. 
They should be split up afterwards with light charges of explosive placed in auger holes or between 
roots, under a mudcap. 

probably will outlast you if you do not move them. In case of a locust stump 
in Oklahoma, you know that you have a lateral root stump to deal with, that 
will sprout and that will last as long as the white pine. These illustrations 
serve to point out how every reader can classify his own stumps as to facts 
about them that are important from the clearing standpoint. 



Methods of Clearing Land of Stumps 

A half-dozen methods of removing stumps are more or less well developed 
throughout the country. Everyone who clears land, whether it is only the re- 
moval of stumps from cultivated fields or the clearing up of logged-off areas, 
should study the different systems in order to decide which of them is best 
under any particular conditions. No one method is best all the time, and in 
nearly every case a combination of various means will be found most effective. 



Lists of Methods 

Digging out the stumps by hand. 

Pulling the stumps. The pulling may be done with horses or machines. 
The pull may be direct, or may be doubled or tripled in force by means of 
blocks and cable or rope. If with machines, it may be with a traction 
engine hauling direct, a donkey engine hauling by means of a drum and 
cable, a capstan puller run by horse power or man power, or a tripod 
puller which lifts the stumps straight up. (See pages 44 to 50.) 

Burning the stumps. The old-fashioned practice was to start a fire along- 
side a stump and keep it going till the stump was consumed. Charpit burning 
consists of keeping an intensely hot but small fire about the base of a stump 
under a covering of earth. Another method is to bore auger holes through the 

41 



stump or part way through, to form draft holes and flues. A favorite method 
in some sections is to burn out the roots with a gasoline torch to a depth below 
the plow line. 

Finally, there is the use of explosives to blast out the stumps. 

Combinations of methods very often are valuable, and are recommended 
at proper points. 

Stump Disposal 

The land clearer must remember the necessity of disposing of stumps 
after they are out of the ground. It is expensive and difficult to haul or 
burn whole stumps. Several hundreds of pounds of earth nearly always stick 
to the roots of big stumps taken out unbroken. For this reason wherever it 
is possible to do so the stumps should be broken into pieces small enough to be 
handled easily before the job is considered done. There is no comparing the 
cost of burning stumps, when they have to be piled by means of a derrick, 
with the cost when they can be handled by hand. 



Choice of a Method 

Whether to remove stumps when they are green or to let them decay a 

year or more is a problem to be decided by your plans and the uses to which 

you will put the land. Newly cut-over land is clean. It has 

few weeds and no sprouts. In one season it will not develop 

Green vs. much of this growth, but in two or more seasons it will, 

Old Stumps and will be very much harder to clear than it would have 

been the first year. 

The stumps are hard to take out while they are green. 
It costs much more to do the work then than a year or more later, after the 
bark and sap-wood has rotted from the roots. 

But it costs money to miss crops, too, and if you are ready to put the 
ground to work at once, it is folly to wait for the stumps to rot. To wait from 
summer till the following spring is not a bad idea, for that loses little or no 
time, and starts the rotting process which makes removal easier and cheaper. 
Speaking in general of pulling and blasting, pulling the stumps probably 
is better and cheaper when the stumps are very small, and blasting when they 
are large. Where a large number of big stumps are to be removed a 
combination of the two methods is advisable. 

When stumps are small or numerous they can be pulled by a team of 

horses hitched direct, by a capstan puller, traction engine or donkey engine, 

with ease and speed. The pulled stumps can be handled by 

hand directly, and disposed of without trouble. The same 

Pulling and is true to a lesser degree when larger stumps grow small and 

Blasting shallow roots, which require but little power to lift and move. 

For stumps larger than 3 to 5 inches, explosives can 

be used alone effectively and economically, though there are 

important considerations which modify such a rule. One of them is that of 

soil. Explosives work more effectively in heavy, tight soil, such as moist clay, 

than in dry sand. Therefore, in dry, light soil it often is cheaper to pull all 

the stumps not too large to handle without breaking up, while in heavy soil it 

usually is cheaper to pull only very small stumps that will come out easily, 

and to use explosives, alone or in combination, for everything larger. 

42 



Old, well-decayed stumps too big to handle should be removed with ex- 
plosives alone. Small green stumps may be blasted out clean, roots and all, 
but large green stumps nearly always require a combination of methods, as, 




This picture shows how the roots of large green stumps can be broken up for handling by proper 
blasting of the stumps. There is little reason in clearing a piece of land twice of the same stumps— . 
once to free them from their beds and again to dispose of them — by pulling— when the job can be com- 
pleted with half the trouble and expense by blasting and hand piling. 

for instance, blasting and team pulling, or pulling with a capstan puller. The 
cost of explosives often can be cut down by making use of such a combination 
of methods. A heavy team, or other means of pulling, will take out roots 
after the ground has been loosened with explosives. 

Tap-root stumps larger than your arm should be blasted. Tap-root 
stumps cannot be pulled to advantage, though when very small they can be 
broken off by a side pull. Where land is swampy on the surface, and roots 
consequently lie shallow, a heavy team often can rip out stumps by direct 
pull, even up to fifteen inches in diameter. 

Large stumps that are pulled may be broken up afterward with small 
charges of explosives placed in auger holes, but in general it may be stated 
that large stumps should be blasted first. 

The folly of pulling out stumps that are big, and then spending as much 
money in getting rid of them as it costs to pull them, will be plain to any one. 
They can be disposed of at a fraction of the cost when they are well broken up. 

A more detailed consideration of the pulling of stumps probably is de- 
sirable. Pullers are most successful in the loose jack pine land of the North 
and the similar pine land in the South, and in clearing hardwood cut-over 
land where nearly all the stumps are small. They are 
particularly serviceable where the stumps stand close to- 
Capstan Puller gether, measure 3 to 6 inches and have root systems which 
do not bring up much dirt. Under such conditions a stump 
puller is a good investment, especially where there is plenty 
cf man and horse labor available at low cost. 

But it does not pay to buy a machine for a small acreage of clearing. It pays 
only where a considerable quantity of clearing is to be done. In vicinities 
where the soil is light and there are many stumps on newly cut-over land, 

43 




Two large hardwood trees which stood close 
together and were blasted out at one shot, without 
cutting down. About eight charges were used. The 
cavity in the ground is small and the soil is free from 
tight roots. 



several farmers should co-operate in the purchase of a stump puller and should 
help one another to use it. 

A stump puller works to least advantage under clay soil conditions. An- 
other factor is the water in the 
ground. The ground must be fairly 
dry when the machine is used, even 
though the stumps require harder 
pulls then than when the ground 
is water-soaked. In mud, horses 
soon become mired deeply. Pull- 
ing of stumps must be done in the 
summer or fall. Of course, they 
cannot be pulled when the ground 
is frozen. 

A capstan puller can be used 

on a moderately steep hill, though 

the cost of pulling the stumps from 

such ground will be greater than 

from level land. Whenever it is 

desired to use a stump puller, have 

explosive materials on hand to 

blow out or to split and loosen any 

stump larger than about 5 inches. 

A donkey engine outfit especially designed for stump 

pulling can be used effectively and with success. It makes 

Donkey Engine an expensive outfit, however, and unless there are several 

hundred acres of clearing to do, consideration of it may be 

dropped. In the case of very large acreage, it is the logical 

form of capstan puller to use. 

A traction engine, pulling stumps direct, is a very effective means of get- 
ting stumps out. In fact, when such an engine is available it is doubtful if the 
purchase of any other machine ought to be considered. 
Both traction and donkey engine pulling is subject to the 
same limitations as pulling by any other means, and 
should be confined to such work as they can do to ad- 
vantage in comparison with explosives or other methods. 
The detailed consideration of the blasting of stumps may be short and to 
the point. The use of explosives reduces the labor of land clearing greatly. 
One or two men with explosives can do the work of a large crew with pullers 
or fire. 

The stumps can be blasted out clean. Thousands and thousands of acres 
of stump land are cleared completely every year with ex- 
plosives alone. While the use of some means of pulling 
When to Blast in connection with explosives undoubtedly cuts down the 
cost on a large tract of clearing, the added ease and speed 
of the work of explosives alone is considered by many 
people to offset this economy. For small tracts or a few stumps it is foolish 
to provide pulling facilities. Do the work with explosives. 

The blasting splits the stumps into pieces easy to handle, and to sell or 
burn. When it is not desired to blast stumps out clean, the charges can be 
kept down and the stumps split and the dirt loosened and thrown away from 
the roots. The blasting does the work in a short time. 

44 



Traction Engine 



The investment of money is 
kept down when explosives alone 
are used. There is no machinery or 
equipment left on your hands after 
the clearing is done. Yet the best 
use of stump pullers and of explo- 
sives is mainly distinct and differ- 
ent, and they should be considered, 
not in competition, but in combi- 
nation. A good team and a supply 
of explosive material is a winning 
combination nearly every time, and 
explosives are bound to play an 
important part in nearly every 
land-clearing operation. 

Digging out stumps is practi- 
cable under certain exceptional cir- 
cumstances. If you cannot get 
explosives and if you have men 
who are doing nothing, they may 
be put to digging out stumps; but 
if wages have to be paid, such 
clearing is bound to cost four or 
five times as much as when the 
work is done by better methods. 





This pine stump is burning freely, and likely will 
be consumed if it receives some attention. The roots 
were bared of dirt and the stump was split by a 
light charge of explosive. When stumps can be 
left to dry for a couple of months after such splitting, 
they will burn very well, though pine stumps can be 
burned immediately afterward with a little coaxing. 



Big stumps such as this can be blasted 
out electrically much easier and better than 
with charges fired with fuse. 



Burning by charpitting is a 
practicable and cheap method of 
getting rid of soft wood stumps of 
large size and of stumps in heavy or 
clay soil when the weather is dry 
for two months or more at a time. 
It is not successful in lighter soils. 
It is costly when labor must be 
hired for the purpose, and wastes 
time. This method of removing 
stumps is chiefly valuable for 
settlers of logged-off or cut-over 
land who must fight their way 
through with little or no money. 

Burning by 
means of auger 
When to Bum holes, and the 
use of oil, are 
freak methods 
not suitable for general use. They 
should not be attempted when 
the clearing operation is seriously 
intended to be economical. Burn- 
ing with a torch of some kind is 
effective, but expensive. 



45 



Detailed Directions for Clearing Land of Stumps 

Digging Out Stumps 
If you dig right down after the roots, trenching to bare them, cutting them 
off with an axe first at the sides and then underneath, the stumps can be 
rolled out as though they were pulled. The cost is high. 




Typical tap-root stumps, with the dirt washed away. To blast them out the charge must be 
located against the big root, four or five feet below the surface of the ground. Two charges to each root 
are better than one, though either loading will cut the root off successfully 

If possible to know beforehand that you must dig stumps out, do it be- 
fore the trees are cut. Dig a trench about them, 
taking away the support, and cut the lateral roots, 

Trench about Trees and then let the wind and water finish the job. The 
water in the trench will soften the subsoil. The best 
time of year to do it is in the spring, when the wind 

is strong and the ground is loose. 

Burning Out Stumps 

Charpitting is perhaps the best method of burning stumps. The fire is 

kept burning at the base of the stump till it burns entirely through, and till 

the top is consumed as it settles down and the roots are eaten 

out to a proper depth below the surface of the ground. The 

Charpitting fire is confined by a covering of earth. 

Charpitting is effective only when heavy grounds can be 
secured to cover the fire. Sand, loam or other light soil cannot 
be used for the purpose successfully. 

The stumps should be reasonably dry, and the weather should be dry 
during the burning process, which takes two to six weeks. Light showers are 
not objectionable, but heavy, settled rains cause failure. Pine stumps burn 
best, because of the pitchy nature of the sap remaining. Any 
other soft wood can be burned this way. The successful burn- 
Conditions ing out of hardwoods requires favorable conditions in all re- 
spects, and is rather doubtful in the hands of inexperienced 
operators. 

46 



The procedure is as follows: Remove the bark from the base at least. 
On some stumps it is necessary to dig away a little dirt. The fire should be 
started low enough so that it will burn in under the stump at the spaces be- 
tween the roots. 

Gather some fuel wood — any kind that will make good 

coals, though mixed oak and a little pine likely will be best. 

Directions Cut this wood like stove wood — say about a foot long, and split 

fairly fine. Lay and stand the sticks round the stump till you 

have a layer at least 6 or 8 inches thick. You can pile wood 

and start the fire entirely round the stump, or only about a quarter of the 

way round as you prefer. Putting wood all round takes more wood 

and more time to prepare, but burns the stump out quicker and has more 

chance of success. 

After the wood is in place it must be covered with a little straw, fern or 
other material of the kind, and then with a thin layer of dirt. The dirt layer 
should not be more than 3 or 4 inches thick. It must be of clay or very heavy 
soil. The dirt should be piled against the stump up to about 18 inches high, 
but no higher. 

Start the fire at each quarter of the space round the stump. That is, if 
the wood runs only a quarter way round, start one fire; if all the way round, 
start 4 fires. Leave the holes where the fire is started open only for a little 
while, and then cover them up. 

The fire must be kept covered all the time and never be allowed to burn 
into an open blaze. It is really smouldering and coaling of the wood. When 
the fire blazes much of the fuel supplied is burned up and the heat is lost in- 
stead of forced to eat its way into the stump. The object is to confine 
the heat. When this is properly done the fire becomes intensely hot round 
the stump. 

As the stump burns through and the fire goes deeper, the dirt cover may 
break through. Such places must be covered with more dirt. If the fire burns 
higher up the stump than where the dirt is piled in the first place, put it out 
up there instead of trying to pile the dirt higher. 

As soon as the stump is burned through, the top will settle down and con- 
tinue to burn. Keep the fire covered over the ends of roots that burn off, so 
it will eat its way deep into the ground. If it breaks out to the air it will not 
burn far. While the stumps are burning they must be watched and visited 
several times a day. 

The cost of charpitting in the manner described is high when the actual 
time of the operator must be accounted for at regular rates of wages. 

Another good method of burning that really is charpitting of a modified 
form, is to saw the stumps off close to the ground, block up the top part, and 
to start a fire between the two sawed faces. The faces 
should be as close together as possible while allowing 
Idaho Charpitting the fire to be started and to burn. Bank up the out- 
side with dirt, as directed in preceding paragraphs, and 
keep the fire covered till the stump, roots and all, is 
consumed. Use stones to hold the two parts of the stump apart. It is best 
to do the sawing in the winter and raise the top part then, leaving it to dry 
out several months. The burning is done best in the summer. 

47 



Burning with a torch is simply a matter of digging away the ground from 
the roots, and applying the intensely hot flame at a point 
below the plow line. Torch burning is expensive business 

Torch Burning when time and fuel costs are counted up. The best kind 
of a torch to use is one with a fan or bellows. The kind 

of fuel used by the torch is not important, except that some fuels burn 

better than others. Gasoline perhaps is best. 

A modification of charpitting sometimes is advisable in the case of pastur- 
ing the land for several years. The stumps are split and their roots un- 
covered with small charges of explosives. When they 
are thoroly dry, wood is piled between and over the split 
Plain Burning tops of the stumps and the whole thing is set on fire. 
With a little attention to keeping the burning ends of the 
roots covered with ashes and dirt toward the last, stumps 
may be consumed entirely by this method. It is not nearly so much trouble 
as charpitting, because the fire burns fiercely in the dry, shattered tops, and 
needs no attention other than the first piling of the fuel till it is time to look 
after the burning out of roots. 

Pulling Out Stumps 

Four forms of pulling are worth considering. These are by horses direct, 
with hand pullers and capstan pullers, and with donkey engines and traction 
engines. 

A good heavy team of steady horses will take out most of the stumps which 
should be pulled whole, and almost any roots left by proper 
use of explosives where blasting and pulling are used in 
Four Forms combination. You will need a couple of good log chains 
of Pulling and a regular outfit of singletrees and spreaders. To in- 

crease the strength of the direct pull, you can use a 
frame made of 6 by 6 pine pieces in the shape of the letter 
A. Make it 6 feet high. Attach a short piece of chain round the tip of the A, 
to run down to the roots over the top of the stump, or else run the main chain 
from the horses over the top of this frame before attaching to the stump. Such 
a haul will upset a stump much easier than a direct hitch. 

If you have to pull without the frame, aim to pass the chain over the top 
of the stump and hitch to a root on the other side, the farther out the better. 
Another good hitch and haul is the twist. Hitch to a root and drive so that the 
chain tends to wrap round the stump. 

When saplings are to be removed do not cut them first, but 
hitch the chain to them as far up as you can reach. While the team 
is hauling on them, a man should cut the roots on the opposite side with 
an axe. 

A few days of stump pulling is enough at one time. Rest the 
horses and men at some other work. The clearing of land by this method 
is heavy and tiresome, and can easily become disheartening if kept up 
too long. 

A capstan puller consists of a frame, a drum on bearings, a pole to hitch 
horses to, and a wire cable fastened to the drum. Some of them have gearing 
which reduces the speed of the drum and increases its pulling power. These 
work very slowly. 

48 



The pullers have to be anchored to solid stumps near the place where 
they are set up. The limiting factor in the use of pullers 
is this anchor or anchors. When you pull, you do not 

Capstan Pullers always know whether the stump out at the end of the 
cable or the one behind the machine will come. To set 
the machine takes time, and you should be careful to 

make the anchorage as secure as possible. 

If your puller comes without a pole, you can get one in the woods near 
home. Cut a 6-inch tree — ash, white oak, hickory or the like — and use a 
20-foot length. Better attach an old wagon tongue to this where the horses 
are to be hitched, to keep the pole from hitting the horses when stumps give 
way suddenly. Some operators also attach a second pole in front of the horses, 
to lead them in the circle, saving continued driving. 

It is better to wind up the cable on an empty drum; the cable 
wears much less in this way. For that reason use only enough cable to 
cover the drum — not two layers on it. The length of the cable will govern 
the area you can clear with one set of the machines. This usually will be 
about an acre. 

Three men can clear an average acre of cut-over land of small stumps in 

one day. Three men will handle a small outfit. Handling the cable is heavy 

work, and you want no boys on the job. The hooks for catching the roots 

that come with the machines usually are poorly designed. You can have a 

better one made by welding together two old steel plowshares in a manner 

that your blacksmith will understand if you show him the 

original hook. For best results a hook should weigh about 

Time to Pull 50 pounds, though to be so light it must contain only good 

steel. 

Pullers are not suited for taking out occasional stumps in 
cultivated fields, but only to clearing cut-over land where stumps stand close 
together. The machine should be brought on the job only after the necessary 
blasting has been done. Then the small stumps and whatever roots are left 
by the blasting can be taken out at the same time. A supply of explosives 
should be kept on hand for blasting out the anchor stumps after the machine 
has done all the work it can. 

A tripod puller is effective, but cumbersome to handle and expensive to 
operate. It is not recommended. 

A donkey engine for stump pulling should have about the same 
power as for logging operations, and should be constructed about the 
same. There should be two drums, one for the pulling cable and the 
other for the return line, the return drum geared faster than on a logging 
donkey. 

About 350 feet of pulling cable can be used. Inch or inch and a quarter 

cable usually will be best. The return line would be 

Donkey Engine half or five-eighths inch. With 350 feet of main cable, 

Outfit 10 acres can be cleared at one setting. It speeds up 

operations to use a cluster cable with three or four 

books. Several small stumps can be pulled at once with this. 

A donkey engine outfit requires five or six men to operate it. With it 
stumps of any size can be pulled. When they are too big to handle directly 

49 



Traction Engine 
Pulling 



it is best to break them up with explosives before attempting to burn or other- 
wise dispose of them. Very large stumps should be loosened and split before 
they are pulled. 

Little needs to be said about using a traction engine. You will need heavy 
chains and heavy hooks. The chain should be nothing less than five-eighths 
inch. A short piece of inch or larger wire cable is better. 
Fifty feet or so is enough. The hook should be of steel, 
with one point, and should weigh 50 to 100 pounds. The 
entire hitching apparatus should be strong enough to 
stand jerking on with the weight and power of the 
engine. 

The cost of operating pulling machines and of clearing land with them 
varies so much that no figures are safe to depend on. It depends on 
the kind of soil, the kind of stumps and especially on the skill with 

Cost which the machines are operated. When everything is at the very 
best, land can be cleared economically with donkey engines and trac- 
tion engines in combination with explosives. When conditions are 

not favorable the cost of these methods is very high. 

For any kind of stump pulling you will need shovels, hoes, axes 
Tools and bars. The probing rod also is useful for locating roots. 

The directions for removing stumps with explo- 
sives are given in full detail, and in order to do the 
matter justice they are placed in a separate chapter. 



Blasting Out Stumps 



Blasting Out Stumps 

A proper charge of explosives placed under a stump will tear the roots loose, 
lift the whole stump out, and break it into pieces. The whole operation is 

simple, safe, short and easy. Any 
sort of stump, of any size, in any 
soil, any weather, can be blasted 
out successfully, and the blasting 
is a practical and efficient method 
whether there is one stump to be 
removed from the middle of a cul- 
tivated field or a lawn, or thousands 
of acres of the heaviest logged-off 
land clearing to be done. 

The best time of the year to 
blast out stumps is a matter of 
compromise between conflicting 
requirements. On the one hand 
explosives work most effectively in 
moist clay and wet sand soils. On 
the other hand, it is bad from a 
tillage standpoint to blast heavy 
ground when wet. (See page 67 
for further discussion.) 

With all the facts before you, the selection of time is a matter for your 
own judgment. If cost did not need to be considered, summer or fall would 

50 




It is folly to attempt to blast out many big 
stumps, such as this one, without an electric blast- 
ing machine. Such a stump should have six to eight 
charges properly located about it. These numerous 
charges will contain less total explosive than one 
charge large enough to remove the stump. The hole 
they make is much smaller. 



Time of Year 



be ideal. Blasting out stumps from frozen ground can be 
done with satisfaction. In fact, the stumps are broken up 
better then than at any other time, though the work is 
harder on account of the difficulty of making holes. 

Success, and especially economy, in stump blasting, is a matter of common 
sense and judgment plus some knowledge of the stumps and of explosives. 
Close attention to apparently small matters insures good work. The things 
that the blaster must consider are the location for the charges, the proper size 
of holes, the amount of explosives required, the length of fuse, depth of hole, 
tamping and the like. 

Loading Charges of Explosive 

To blast out a stump the explosives must be placed in a hole underneath 
it. Make the hole first. Then prepare the charge of explosives as directed 
on pages 142 to 150. Pack the explosives in the hole, tamp and fire. 




In blasting out big green stumps, the holes for the three to eight charges should be made as nearly 
as possible under the main anchor roots. The man on the right is smoothing out a hole, getting it ready 
for the charge; the one on the left is shoving a cartridge home with the tamping rod. 



Load stumps by no rule, but with regard to their root systems and to the 

nature of the soil. The aim is to tear the roots out of their anchorage in the 

ground, or to break them off below tillage depth. To do this you must place 

the charge or charges of explosives as close to their 

burden as possible — hitch them as short as possible to 

Depth for Charges the load. The load or burden is not the weight of the 

stump so much as its grip on the ground. You must 

get good confinement of the gases. If there is a weak 

wall on one side of an explosion and a fairly solid or firm wall on the other, the 

weak wall will give way, and very little breakage or movement will be made 

in the other. 

The charge of explosives should be located just deep enough to secure this 
confinement and to be under the load to be lifted, but not any deeper. If 

51 




charges are too deep there is great waste of energy in uselessly lifting earth. 
This is costly. Charges that are placed too shallow will blow off the tops of 
stumps or split them, leaving roots tight in the ground. 

Since clay and other heavy 
soils hold the gases much better 
than sand, and wet ground holds 
them better than dry ground, a 
much thicker covering of dry sand 
is required over a charge to confine 
the gases properly than of wet 
clay. Charges, therefore, must be 
placed deeper in sand. Usually the 
charges should be placed right next 
to the wood of the roots in clay 
soil, and in sand with 6 to 30 inches 
of ground between the charge and 
the roots (tap roots excepted — see 
next page). Large stumps, and old 
stumps, require shallower placing 
of charges in proportion to diam- 
eter than small stumps and green 
stumps. Long-rooted stumps re- 
quire deeper placing than short- 
rooted ones. 

With the foregoing points in 
mind, it will be seen that the 
charges should be placed directly 
under that part of the stump that 
will give the greatest resistance. 
This may be the center, but it is by no means always so. If the stumps 
have grown on a hillside, the roots may be heavier cut sideways than 
uphill or downhill. Very often a tree on the level has heavier roots on one 
side than on the other. Usually it is of advantage to blast a big stump 
with more than one charge, placing one charge under each of the large roots 
and one under the center of the stump. A charge under a root should be at 
a point where the weight of the stump will be balanced by the pull of 
the ground at the other end. This point usually will be a foot or two out from 
the edge of the body of the stump. 

In the foregoing suggestions, no mention has been made of the three main 
types of root growth — tap-root, semi-tap root and lateral root; but with the 
principles of blasting in mind, it is easy to see that a properly placed charge 
under a lateral root stump will be very shallow. If such a stump is to be taken 
out with several charges instead of only one, all but one of the charges will 
have to be located well out from the stumps proper, under main roots. 

Semi-tap root stumps require deeper placing of charges than lateral root 
stumps. When such stumps are taken out with more than one charge, the 
points for the explosive are closer in, under the main roots where they dip a 
couple of feet below the surface. 

The underground nature of each stump should be determined before plac- 
ing charge or even making holes. You can do this partly by observing the roots 
that rise above the surface, but mostly by probing down among the roots with 

52 



The charges are placed and the wires connected, 
the stock has been chased away and the helpers 
warned back — now the blaster is ready to shove the 
handle of his machine down and to fire the explosive. 




How cartridges of dynamite swell and fill the hole 
when they are split and pressed with tamping stick. 



the quarter-inch steel needle known as a probing rod. Every blaster should 
have one of these rods and should make use of it at each stump. 

There are two ways of blasting 
out true tap-root stumps. One is 
to bore a hole in the wood of the 
tap-root itself, and the other is to 
place the charges right alongside 
the root and against it, as mudcap 
charges are placed in stone blasting. 
In placing the charge in the wood, 
make a hole in the ground down to 
a point a couple of feet below the 
surface of the ground. Then bore 
a hole in the wood with a wood 
auger. This hole should go two- 
thirds or three-fourths of the way 
through the root. Fill the hole in 
the wood with explosives, fire, and 
the resulting blast will cut off the 
root. 

In placing the charge of explo- 
sives against the wood, get it at 
least 4 feet deep. If you can com- 
mand an electric blasting machine 

for firing, divide the charge in two and place the two parts on opposite sides. 
These charges may be placed only 33^2 feet deep, though you should not hesi- 
tate to place the charges at a greater depth when blasting large tap-root 

stumps, particularly if the ground 
is of a light nature. 

In all sorts of stump blasting 
the holes for the charges can be 
dug with narrow-bladed shovels, 
spades or crowbars, or bored with 
dirt augers. (See page 61.) In 
stony land augers cannot be used, 
or can be used only for parts of 
the holes. All 



things consid- 
Making Holes ered, it is hard 
to beat the bar 
and sledge com- 
bination for making holes for 
charges of no more than two or 
three sticks, or for starting holes 
for larger charges. 

The bored hole is better than 
the dug one because it can be 
tamped tighter. After much dirt 
once is taken out, it will not be 
tamped back in again as solid as it 
was before. Holes for inch-and-a- 
quarter cartridges of explosives 




How to place charges for blasting out tap-rooted 
stump. Three methods are shown. "A" shows how 
to do it with one charge, using cap and fuse and not 
boring into the wood. "B" shows how to place two 
charges when electric blasting machine is available. 
"C" shows by dotted lines position of auger hole in 
wood where one charge could be placed to cut off 
the root and throw out the stump. Any one of the 
three methods will do the work. 



53 



should be made with inch-and-a-half augers or bars. In blasting exceptionally 
large stumps, use 2-inch or 3-inch augers. The holes usually can be started be- 
tween roots and in depressions, but do not sacrifice good placing of charges for 
ease in making holes. 




How to place charges under lateral rooted stump. "A" shows how to place charge when the cap 
and fuse are used and one charge is relied upon to remove the stump. "B" shows how to place 
three small charges under main roots when stump is to be removed with several charges fired by electric 
blasting machine. Use either method "A" or " B " — never both. 

In water-saturated ground of a heavy nature, in case you have difficulty 
in getting the charge properly centered or placed (when no electric blasting 
machine is available for firing), you can make use of what is known as propa- 
gated detonation. Divide the big charge into several small ones in different 
holes bored from two, three or four sides of the stump, but all ending close 
together down under at the right point. If these charges are tamped solid and 
they are not more than a foot apart they all will explode at once when one of 
them is fired with a cap and fuse in the usual way. 

In making holes for blasting out tap-root stumps, start the bar or auger 
straight down along the root from the surface. When you have reached the 
required depth, wriggle the bar sideways to make the hole wide at the bottom. 

Wherever the number of stumps runs into many thousands, it will pay to 
get a machine to bore the holes. Such a machine will bore all the holes needed 




How to place the charges under semi-tap-rooted stumps. "A" shows proper position where one 
charge and cap and fuse are used. "B" shows proper positions of several small charges when electric 
blasting machine is used. Use either one or the other method illustrated — never both. 

54 



under the stumps at the rate of 500 or 600 a day, and at very much lower cost 

than the same work can be done for by hand. The machine 

bores almost as fast in wood as in earth, and is particularly 

Power Boring serviceable when roots have to be penetrated in order to 

get the charges to the right spots. 

Machines can be bought complete in small sizes suited 
to land-clearing purposes, or can be bought in parts and assembled on home- 
made frames. Electric machines are most convenient. Steam and compressed 
air machines are next best. Flexible shaft machines and direct-geared machines 
are least satisfactory. The flexible shafts break. The steam outfits freeze up 
and are troubled with burst pipes. All the outfits except steam ones can be 
run by gasoline engines. 



■■ ''wis- 



' ; MiM^ 




To show cartridges of explosives expanded, as permitted by splitting of cartridge wrappings, in big hole. 



An electric boring outfit consists of a small gasoline engine — say about 5 
horse power — on a wagon belted or geared to a 3 kilowatt dynamo, and that 
equipped with two drill heads and 200 feet of electric cable. A supply of V/t 
inch augers completes the outfit. Such an outfit costs about $500. You can 
use any gas engine. The dynamo will cost somewhat less than $250, and the 
drills about $80 each. 

It takes five men to run this outfit — two men on each drill and one man 
to drive and to handle the cables. This man should lift the cables carefully 
over stumps and prevent them from kinking and getting caught. The steam 
and compressed air and the direct drive machines will not be described, be- 
cause improvements continually are coming out. Watch the farm papers for 
advertisements, or write to any maker of explosives for names of manufacturers 
of these machines, if you are interested in them. 



55 



Study the methods of handling explosives as outlined on pages 1 44 to 1 50 
and 1 67 to 1 70, to which every reader is referred at this point, before trying to 
load charges. A few special hints will be given here. 

Charges of explosives usually should be as near as may be in a round bulk — 
not strung out for 2 or 3 feet in a long hole. To get them so the hole must be 
enlarged at the bottom by scraping or springing. Slit the paper 
Slit wrappings of the cartridges and press the cartridges in the hole 

Cartridge with the tamping stick till they swell to fit the hole tight and 
Wrappings shorten to 2 to 4 inches in length. (See pages 53 to 55.) But do 
not do this if the hole is very wet. 

When you have many stumps to blast out, it often is a 
good practice to make holes in the forenoon and then to load and shoot after 
dinner. Load and fire all the holes you have prepared when you go to the 
field, after which you can proceed to make more holes. Always fire the charges 
soon after they are loaded. To do this prevents missing charges, and avoids 
chance explosions due to meddling, and the like. If the holes are wet, firing 
immediately is required to avoid weakening of the explosive by water. 

If you prepare your charges in the field, you can cut a supply of pieces 
of fuse before you go out. Make the pieces of varying lengths and crimp caps 
on them to prevent the powder shaking out of the ends. Take the roll along 
with you to provide for holes requiring longer fuse. Don't attempt to use 
pieces of fuse less than 1 5 inches long. They are dangerous. 

Use plenty of earth when tamping the holes, and tamp well. See that 
the ground is packed solid, not only where you made the hole, but all around 
the stump. Often there are holes dug by skunks, groundhogs, gophers, squir- 
rels, rats or mice under stumps. 
Keep the charge of explosives away 
from these cavities — better fill them 
up. 

In lighting many fuses a gas- 
oline or oil torch is useful. But 
there isn't anything much better 
than to stick the burning end of a 
freshly scratched match right 
against the powder in the end of 
the fuse. (See page 1 59.) Remem- 
ber that the outside cover of the 
fuse does not burn, but the spark 
runs down the center as a drop of 
water might run down a tube. Do 
not leave the fuse till it spits sparks 
regularly. 

None of your charges are likely 
to misfire if you load carefully, and 
if you have taken proper care of 
your explosive materials before 
loading. But if misfires do occur 
with fuse, do not investigate them 

Some such appearance is necessary in stump r cpvpra | Knurs at lpast fS*>p 

blasting, but the less of it there is the better. The tor several nours, at least, ^oee 

ideal blast is just strong enough, and is so located, page 164 for discussion of misfires.) 
that it rolls the roots free of their beds and splits p.r . , 

them apart, but does not throw them an unnecessary Ul course, in elec- 

foot. Loud reports and much dirt high in the air MicfirpQ trir firincr ™-ni ran 

show careless loading and useless expense. iviibnreb trie nnng you can 

56 




investigate a misfire immediately after the wires have been disconnected at 
the blasting machine. 

Amount of Explosives Required to Blast Out Stumps 

A proper charge of explosives for a stump blast has a dead, muffled report. 
It lifts out and splits the stump. Loud report and the throwing of the pieces 
far shows that too much explosives has been used. When stumps merely are 
split and tight roots are left, not enough explosives has been used (or it may 
be placed too shallow). If the explosion is muffled and does not throw pieces 
far, but digs too big a hole, the charge is too heavy and too deeply placed. 

It is impossible to lay down exact rules for the amounts of explosives to use. 
This bulletin will include figures of amounts that have been used to blast out 
some stumps, but these figures must be regarded as correct only under identi- 
cal conditions of soil, kind and age and size of stump, amount of water in soil, 
kind and grade of explosives, and amount of confinement in the hole. Experi- 
ence must be the teacher in this matter. 

A green stump requires a great deal more explosive than one that has 
stood a few years. More explosives are required in stony land than in smooth 
land to blast out stumps. The harder and heavier the soil is, the less explosives 
are required, and the looser and lighter it is the more explosives are required. 
Dry soil requires more explosives than moist soil. 







S»«4P 



$$**** 



As these roots lie, they show the result of an almost ideal blast. There is little hole in the ground; 
the stump is well broken up; the roots are cleaned of dirt; and no roots have been thrown very far. 

When you want to blast a stump entirely out, it is better to load 
too heavily than too lightly, for roots left tight in the ground after the top of 
a stump is blasted off are hard to get out. If you are not familiar with stump 
blasting, start with the small stumps and load them as you think they should 
be after considering the various points explained in foregoing pages, and in 
view of the following figures. 

Ordinarily it takes one pound of explosives for each foot in diameter of 
stump, when the stump is such as a white pine in clay soil cut 10 years 
or longer. Green stumps of any kind require more than this — usually about 
half again as much; sometimes twice as much. A rule for the enormous stumps 

57 



of the Pacific Coast is to square the diameter of the stump, measured in feet, 
and use this figure as the number of \}i by 8 inch cartridges of explosives re- 
quired. This rule usually over-estimates the amount required for stumps larger 
than 3 feet in diameter. 





Examples of the incomplete job resulting from trying to blast out very big stumps having wide- 
spreading roots, with one charge to each one. Unless the charge is excessively heavy, which means 
that it is expensive in explosives and in loading, it can not be placed deep enough to remove the whole 
stump. Even if it is deep enough and heavy enough to be successful it is objectionable on account of 
the big crater made. Each big stump should have several charges. 



Amount of Explosives Used to Blast Stumps 

The following table is taken from records of blasting in Minnesota, Penn- 
sylvania, Oregon, Kentucky, Michigan and Florida. The stumps were blown 
out effectively and successfully, and the figures should serve as a reliable guide. 



Diameter Stump 


Kind 


Inches 


Stump 


10 


Pine, dead 


12 


Pine, dead 


12 


Pine, dead 


12 


Pine, dead 


14 


Pine, dead 


15 


Pine, green 


16 


Pine, dead 


18 


Pine, dead 


18 


Pine, dead 


18 


Pine, dead 


20 


Pine, dead 


20 


Pine, dead 


24 


Pine, dead 


24 


Pine, green 


24 


Pine, dead 


24 


Pine, dead 


24 


Pine, dead 


36 


Pine, dead 


36 


Pine, dead 


36 


Pine, dead 


40 


Pine, dead 


48 


Pine, dead 


48 


Pine, dead 



Kind 
Soil 


Cartridges 1 J 4 inch 
Dynamite 


Clay 


1 


Sand 


IK 


Loam 


1 


Clay 


1 


Clay 


2 


Loam 


4 


Clay 


\Vi 


Sand 


3 


Loam 


2 


Clay 


\Vi 


Sand 


7 


Clay 


4 


Loam 


5 


Sand 


10 


Sand 


5^2 


Loam 


4K 


Clay 


4 


Sand 


10 


Loam 


8K2 


Clay 


7K 


Clay 


7 


Sand 


13 


Loam 


10 



58 



Diameter Stump 
Inches 

48 
60 
8 
12 
12 
15 
16 
16 
18 
20 
24 
26 
27 
27 
30 
30 
34 
38 
30 
36 
40 
48 
72 
60 
15 
10 
15 
24 
16 
16 
20 
6 
8 
10 
12 
15 
18 
6 
8 
12 
15 
18 



Kind 
Stump 

Pine, dead 
Pine, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, green 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Oak, dead 
Fir, dead 
Fir, dead 
Fir, green 
Fir, dead 
Fir, dead 
Spruce, green 
Hemlock, dead 
Walnut, dead 
Gum, green 
Gum, dead 
Black gum, green 
Sugar maple, green 
Snag, dead 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 
Tap-root pine 



Kind 


Cartridges l 1 


Soil 


Dynamit 


Clay 


9 


Clay 


15 


Sand 


\ l A 


Sand 


2 


Loam 


\V* 


Loam 


Vi 


Clay 


w* 


Clay 


3 


Loam 


3 


Loam 


3H 


Clay 


3 


Clay 


2 


Sand 


5 


Loam 


4K 


Clay 


4^ 


Sand 


6 


Clay 


4M 


Clay 


5^ 


Loam 


10 


Clay 


12 


Loam 


20 


Loam 


26 


Clay 


36 


Sand 


32 


Sand 


2 


Loam 


1 


Clay 


33^ 


Sand 


4 


Sand 


5^ 


Sand 


5^ 


Sand 


4^ 


Sand 


Vi 


Sand 


u 


Sand 


1 


Sand 


\y 2 


Sand 


2 


Sand 


2y 2 ^ 


Sand 


i 


Sand 


\ l A 


Sand 


3 


Sand 


4 


Sand 


5 



Charge 

in 

wood 



Charge 

against 

wood 



Proper blasts throw out little dirt. They pull the roots out of the ground, 
-' and permit most of what little dirt they do lift to fall back in the hole. In 
consequence good blasting leaves small holes. 

An excellent plan for any blaster is to carry a notebook and a yardstick 
and keep track of the blasts he makes. Make note of the size, kind, age of 
stump, kind of soil, amount of water, kind and amount of explosives used, and 
the result of the blast, in each case. 

59 



The figures here given will serve as a guide for the first shots. As the 
work proceeds, base your loading on your own experience. 



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Here two charges, fired together electrically, were correctly proportioned and placed except that 
one was located too shallow and too far in toward the center. It should have been out under this re- 
maining root, shown in the picture, which then would not have required pulling with horses or another 
blast. 

Kind of Explosives to Use 
The kinds and grades of explosives best to use for blasting out stumps are 



few, and vary with the nature of the soil. 




The single charge under this stump was placed 
too deep and too much to one side. It exhausted 
most of its energy in the ground far below the roots, 
and then what was left escaped between the roots, 
blowing the dirt away but not having enough power 
to carry the roots with it. 

60 



In a heavy soil an explosive which 
cracks, lifts and heaves is more 
desirable than one which shatters. 
In other words, a slow-acting ex- 
plosive such as 20% ammonia 
dynamite is the best to use. If the 
charges must be exposed for some 
time to water, nitroglycerin dyna- 
mite had better be used. 

In dry, light soils, such as dry 
sand, it is necessary to use an ex- 
plosive that exerts its full force 
before the gases can give way, as 
in mudcapping rock. For that 
reason 50% to 60% ammonia or 
nitroglycerin dynamite is the ex- 
plosive to use. I ntermediate grades 
of soil usually can be depended on 
to hold the gases enough to permit 
the use of the slower 20% ex- 
plosives. 

The above does not mean that 
these grades of explosives are de- 
manded for removing stumps. The 
fact is that stumps can be blasted 
out with almost any explosives 
manufactured ; but the work can 



be done more economically and cheaply if the grades recommended above 
are used. 




Four charges fired together tore this stump loose from its moorings and moved it six feet down the 
hill, but did not break it up. Another charge should have been located close under the center. It can 
be broken up easily now, however, by loading one cartridge charge down in the center of the hollow top. 
THIS STUMP IS A WHITE PINE, CUT 75 YEARS AGO. 



The 20 % explosives, especially the ammonia, leave the ground in better 
condition. A violent and quick-acting explosive tears out large holes in heavy 
ground, and packs the earth about the edges. 

Time Required for and Cost of Blasting Stumps 

A day's work for one man is 30 to 60 average stumps blasted out. If 
three men can work as a crew, two making holes and one loading and firing, 
the number of stumps per man will be much increased. 

The cost of blasting stumps is a variable quantity. Those which blast 
out the cheapest are well-rotted oak or walnut, in moist clay soil. Probably 
the stumps which cost most to blast are green white pine or oak in dry sand. 
The skill and good judgment of the blaster also has much to do with the cost. 

Tools 
The tools you will need for blasting stumps are all common ones. The 
pictures show better what they are like than words can tell. You can use 
grubbing hoes, axes, crowbars for driving and for hand use, soil augers, long- 
shanked wood augers, wood tamping sticks, cap crimpers, water buckets, pocket 




3 U 



61 




This stump came out as a result of a charge that 
was placed too deep and a little to one side of the 
proper position, and is not broken up for handling. 
It can be broken very easily as it lies, by locating a 
one cartridge mudcap charge between the two large 
roots seen in the picture. Had the original charge 
been a foot nearer the surface, the stump would have 
been broken in several pieces and all thrown out. 



This bulletin strongly recommends e 
ever there is enough blasting to be done 



knives, steel probing rods, adzes, 
long-handled shovels, spade shovels, 
spoon shovels, scrapers, spoon bars, 
sledges and possibly other tools. 

An old wood auger does not 
make a good soil auger, though it 
can be used in a pinch. For boring 
in ground an auger should have a 
leading point 2 or 3 inches long. 
Both wood and soil augers should 
have cutting bits that can be filed 
sharp a good many times without 
destroying them. Most blasting 
tools are supplied by all makers of 
explosives, and by hardware dealers. 
Some of them can be made at home, 
by your blacksmith. 

The spoon shovel and spoon 
bars are for tunneling and enlarging 
bore holes. Make them by turning 
up and trimming the edges of long- 
handled shovels. The probing rod 
is a piece of quarter-inch steel 6 
feet long, with one end sharpened 
to a point. It had better have a 
handle turned over, or made into a 
ring. No long description of any of 
these toolswill begivenhere, because 
farmers are familiar with them, 
ectric firing for stump blasting when- 
to justify the purchase of a blasting 




A very old white pine stump blown out with three charges fired together electrically. The stump 
is well torn loose and cleaned, but another charge should have been placed at a point close to the wood 
'under the center, to split the stump for easy handling. 

62 



machine. (See pages 159 and 160.) One to fire up to 10 charges can be ob- 
tained at a moderate cost. If skillfully handled its use will save its cost for each 
500 pounds of explosive fired. Electric firing makes possible work in stump 
blasting that is superior to the work produced by any fuse firing when conditions 
are difficult. The several small explosives help one another. 






'.- . 






i ■ ■ J 




The blaster located his charges under this stump too far toward one side. The result is that the roots 
of the other side are left sticking in the ground and require another blast. 

General Hints 

To blast out standing trees, use about twenty per cent, more explosives 
than you would for the stumps. It is better to blast big trees with several 
charges, firing them electrically. 

When big green stumps are blasted out with one charge placed under the 




The result of an attempt to blast out a very large green stump with one charge. The explosives 
were located deep under the center, but they could not reach out far enough to tear loose the many firmly 
anchored roots. They blew off the top, instead. Such stumps should be blasted with three or more charges 
all fired together electrically. 

63 



center, some of the roots often break off high up, so that they interfere with 
plows. They are better blasted with several charges placed round the edges. 
If you are using a stump puller, split and loosen all the big stumps with ex- 
plosives before pulling them. 

It is more expensive to remove severely burned stumps than those with 
the tops intact. In blasting decayed stumps and those with no tops, fill the 
center cavity with ground and tamp it tight. Then place the charges in the 
usual way. 

In blasting old rotten stumps that have sound roots, you often find the 
center underneath has rotted out, or become so that it is only a mass of punk. 
This material will not hold the gases of the explosives. To blast such stumps, 
better use an electric blasting machine, and several charges, or if fuse must 
be used, place the charges under the roots, or deep under the center, filling 
the hollow center with wet clay or loam. 

Old logs and snags frequently are too big to haul or handle and to burn 
on clearings. Do not waste time cutting them in two, but smash them up 
with charges of about half a cartridge of explosives placed in an auger hole. If no 
auger is handy, put a heavier charge in a notch chopped in the log and cover 
with 6 inches of mud. 

Fat pine tap-root stumps often may be shattered by charges of explosives 
placed in the top-roots, and the stumps left to dry. After a few weeks these 
stumps will burn like oil pots. 

Many farmers can clear their land with very little loss of time from regu- 
lar work by going about it in a systematic campaign. In an hour or two each 
evening a good many stumps can be blasted out and the work will be a pleas- 
ure. Only one man is needed. By making sure that the charges are rightly 
placed and proportioned to the stump, the roots all will be broken up so one 
man can handle them. 

Avoid working in the fumes and smoke of blasts, which 
Headache will cause headache. Also keep the explosives from touching 
Prevention the skin of your hands, by wearing gloves. 




When the charge is placed too shallow in the blasting of a stump that is newly cut or that has not 
rotted much, the top is ripped off, leaving many tight roots sticking high enough to catch a plow. 

64 



In removing saplings of sassafras and persimmon and stumps with long, 
tough roots that may sprout if permitted to break off in the ground, it often 
is of advantage to explode half cartridge charges a couple of feet under the trunks. 
This will not take out the trees, but will loosen the ground so that when they 
are pulled over in the usual way the roots all will come away. 

Be careful not to miss charges that are placed, when you are lighting fuse 
or connecting wires. Get them all as you pass the stumps they are under. 
Unfired charges are liable to weakening and damage, and are sources of danger. 




8$ 



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This is what the stump field should look like after the roots have been blown out. If the land is 
to be farmed, the next plowing should see every root removed. 

Stumps make good fireplace wood and kindling wood. You likely can 
sell fireplace wood in nearby towns by doing a little advertising or inquir- 
ing of people you know. Pine stumps have won a place 
in the hearts of all American farmers as kindling wood. 
Stump Disposal On nearly every farm and at nearly every home it pays 
to keep a large supply of pine roots for kindling. Don't 
destroy stumps when your wood-house is empty. 
At many points roots can be sold as fuel for engines. In many parts of 
the South stumps can be sold for turpentine extraction. Everyone should make 
an effort to sell or to use his stumps rather than to destroy them. They 
represent real fuel value, and a little effort usually will get it out. The 
home kindling pile can be made big enough to last for years. The roots are 
ready-cut kindling of the best grade. As fireplace wood they are superior to 
top growth, because of mineral elements in the sap. They make as good 
fuel for lime kilns as any other wood. The price for home use near large cities 
often is upward of $8 to $12 a cord. For turpentine extraction the roots are 
worth at least $3.50 a cord. Farmers themselves can afford to pay at least 
$1.50 a cord, with the cost of hauling added, rather than to burn the stumps. 
But when stumps cannot be sold or used they must be burned on the 
ground. Where they have been pulled out, without breaking up with explo- 
sives, and are large, the pulling engine or horses must be used to pile them, 
with the help of a derrick or gin-pole. An engine and a winch, using a cable, 
is a very good outfit for this purpose. A derrick may be a tripod with legs up 
to 40 to 45 feet long, or it may be a swinging boom derrick, with mast up to 

65 




Wood is a very expensive commodity in many parts of this country to-day. It never will 
get cheaper. Utilization of all parts of the trees that are cut down in land clearing is the thing to do 
whenever it is possible. 

30 feet high and boom 25 feet long. Let the mast lean a little toward the 
pile of stumps, so the boom will swing round itself with its load. Another 
good machine is the Conrath portable piler, much used in Wisconsin. It 
requires 10 pieces of timber or poles, of which the largest, the two skids and 
the boom, are 20 to 22 feet long. A gin-pole may be any height that is 
convenient. An old dead tree makes a good one. Let it burn with the 

stumps piled about it. With 150 
feet of half-inch cable and a pair 
of double blocks the piling can be 
done with horses. 

A better way to handle stumps 
than with a derrick is to use small 
charges of explosives to break them 
up after they are pulled. When 
stumps are well blasted the problem 
of disposal is simple. 

Start numerous small fires and 
haul and pile the roots on as they 
burn down. The fires can be kept 
going till all the roots are burned 
up, by putting on new roots and by 
shoving in butts. Have a wagon or 
sled and keep hauling and unload- 
ing all the time. Drive about the 
clearing on regular routes, each time 
making larger circles and throwing 
off a few roots as you pass by each 
fire. One man can clean up more 
acreage in this way in an equal 
The ideal size and kind of pile for burning time than several men working to 

stumps and roots. These piles can be built by hand, ., , L" L "I - . :«-U 

in unloading the stumps from a low wagon or sled. pile the Stumps in nlgn piles Wltn 

The fires can be started and more roots fed to keep derrick, except in cases where 

them going. r 

66 





^ ' • '/ 


2* jUHfJ^Km 




gsgjRpSKv 









the stumps are large and unbroken, or are left in very large pieces. What 
saves expense is piling by hand. 

When you clear land by blasting, postpone all burning of brush, logs, etc., 
till after the stumps are blasted. Then have a grand burning of everything 
at once. But do not burn the surface — don't let the fire run over the ground. 
Keep it strictly to the boundaries of the piles. There is a whole lot of fertil- 
izer in the layer of leaves, moss, twigs and other vegetable matter that every 
piece of cut-over or logged-off land has on the surface. It is foolishness to 
destroy this. Plow it down. It is worth a good many dollars on every acre. 
When you burn a clearing, first get in touch with the fire warden of the 
district if there is any forested land at all near your place. Use every precaution 
to prevent the fire from getting out of your clearing and beyond your control. 
You will hear — once in a long while — some man say that blasting out 
stumps hurts the soil. When you do, tell him he is mistaken. Proper blasting 

is beneficial to the soil. It is so beneficial that on thousands 

of farms subsoil blasting is regarded as a standard practice. 
Blasting In many orchard sections no one thinks of planting fruit or 

Benefits Soil shade trees without first preparing the ground for them by 

blasting. There is a bulletin published on that subject which 

you should have if you are interested. 
It is proper to add here, however, that when the ground is wet a blast 
does not produce the same effect in it as when it is dry. Subsoil blasting must 
be done when the ground is dry enough to crumble. Blasting a heavy soil 




A good method of piling certain kinds of green roots. Piles even as large as this will prove to be 
more expensive than smaller piles in nearly every instance, and this method is justified only when stumps 
that do not burn well, such as green cypress, pine and fir, have to be burned quickly. 



that is in a plastic condition will make it more compact instead of loosen- 
ing it. It is possible to do damage to a spot in a cultivated field by making a 
hole there — by digging out a stump, pulling a stump or blasting out a stump — 
and failing to fill it up level with the surrounding surface. 

This bulletin states, correctly, that explosives take stumps out most 
efficiently when the ground is moist. While this is true, if you want to 
secure subsoiling benefit to the land at the same time you blast out stumps, 

67 



you must do the work when the ground is at least reasonably dry. By blasting 
the stumps when the soil is not wet you sacrifice some of the efficiency of the 
explosives in the stump removing, and gain in fertility. 

Don't allow the second growth to start at all. Pasture the land with 
what stock you have. To get goats especially for the purpose is practicable 
on large tracts, but the small tract had better 
be pastured by the cattle or hogs or sheep that the farm 
Clearing Sprouts already has. Goat clearing is advisable only where time 
is plenty and money for development is scarce. Cut 
brush to the ground when it is in full leaf. Do the grub- 
bing at intervals through the summer, as time permits. Remember that the 
grubbing must be deep to kill the roots — a foot down at least. 




In this operation four men and five horses are used to pile the stumps. The gin-pole is a modi- 
fication of the swinging boom derrick. The operation is rather expensive owing to its comparative 
inefficiency compared to hand-handling of the stumps when they are well broken. 



After the stumps and sprouts are off the land, there still is some work to 

do before it is ready for crops. New land is fertile, but it usually needs lime. 

The unevenness and stump holes should be filled after 

the plowing is done. A small horse scraper is a valuable 

Finishing Up implement for this, but anything made like a King split-log 

New Lands road drag will do the work. Make a complete job of the 

leveling. Scrape the bumps into the hollows, and make the 

surface as even as possible, so that no water will stand 

in pools. This leveling should be done carefully in old cultivated fields as well 

as in new ground. 

To take full advantage of the big supply of plant food available in the 
soil of newly cleared land, you must plant crops that will bring in money. This 
may be a grain such as corn, but is more likely to be hay, 
cotton or fruit. 
Crops for Strawberries are pre-eminently a new land crop. They 

New Ground never do as well on old land. If you have marketing facili- 
ties for them, put your new ground in strawberries for two 
or three years. 

68 



Potatoes are another paying crop on new land. Corn bears fairly well, 
but not much better than on old land. Other quick-bearing fruits, such as 
gooseberries, currants, raspberries and dewberries, do very well. Vegetables 
like tomatoes, sweet corn, water- 
melons, beets and squash, succeed 
very well. Oats is a very bad crop 
to plant because of the weeds it 
invariably helps to spring up. 

The hay crops are excellent, 
and in some of them there is a 
great deal of profit. Alfalfa is the 
best of them all. If you are plan- 
ning to plant alfalfa, wait two 
years after clearing and plowing, 
meanwhile giving the land a heavy 
application of lime and cultivating 
it in some of the other crops 
named. All the clovers are good. 
Some people like to sow clover and 
timothy mixed. 

On high land sow red clover 
and timothy; on low land alsike, 
timothy and red top grass. Soy 
beans, Canada field peas, field 
beans, cowpeas, mammoth clover 
and sweet clover, cotton and 

tobaCCO, all will yield enormous A type of "gin-pole" used to pile stumps for 

d burning. Often piling by hand in small piles is much 

cheaper. 

If you have cleared in the summer, harrow and disc at once, and sow 
rye, to be plowed down the next spring if you are going to cultivate the land, 
or to be mowed if you sow grass seed. The clover should be sowed on the 
surface of the ground just as the snow leaves in the spring. If you do not 
get a good stand from the first seeding, do not be satisfied with the poor one, 
but tear it up and seed over again. You cannot afford to let new ground 
loaf. There is money in making it work. 




69 





These ditches show the result of cutting the sod and the earth along the sides before the blast- 
ing. Shovel blades, axes and a hay-knife were used. A man cut a rod along one side in about two 
minutes. The blast left the soil outside of the cut firm and intact, while scooping the contents of the 
ditch out clean. (Upper, Miller Drainage District, Marion Co., Oregon; lower, Connecticut land of 
Polytechnic Institute of Brooklyn.) 

70 



THE USE OF EXPLOSIVES IN MAKING DITCHES 
The Matter of Farm Drainage 

Much draining of agricultural land has been neglected because it has de- 
manded so much money, time and hard work, and so many men. The 
excessive cost of ditching has retarded plans to drain, and poor methods have 
retarded actual construction. 

In times past ditches have been made largely by hand shoveling. A few 
of them have been plowed out when shallow ditches could be made to do the 
work at all. But the digging of a few hundred yards of ditch 3 feet deep has 
been a summer's work on a farm, and the draining of land always has been 
very expensive and hard. 

With the increase in the cost of labor, and the scarcity of farm help com- 
pared to the numbers of men that used to be available, there is serious need 
for means of draining that are easier, quicker and cheaper. Since ditching 
with explosives has become well known and generally practiced, it has come 
to be the desired method. 




Observe the even spreading of excavated earth over the surrounding ground, leaving little elevated 
bank on the edges of the ditch. Even in heavy, stiff clay such as this, the explosion grinds the earth 
up pretty fine. (Chester Co., Pa.) 

With few exceptions, ditches can be excavated with explosives anywhere. 
The nub of the whole matter lies in the fact that one of the cheapest ways of 
moving dirt known is with explosives. 

To blast ditches practically all that is necessary is to punch lines of noles 
and push charges to the bottom. The sides and bottoms of the blasted ditches 
are not as smooth as if they were shoveled out, but they are even and true, 
and the flow of water soon levels them down and smooths the bottoms. 

The work can be done quickly, neatly and with no expensive outfit. It calls 
for few men. A month's work by ordinary methods can be done in a day, or 
a week's work in an hour. Ditches can be blasted through any kind of ground 
except dry sand. The presence of brush, grass, stumps and stones is no bar to 
this method of cutting out the ditches, though of course they dig out smoother 
and cheaper when the nature of the ground is clean and clear. 

As for size, ditches of almost any desired depth greater than 1 1 / 2 feet and 
any ordinary width greater than V/i feet can be blasted out. Ditches in fields 

71 





Representative blasted ditches in sandy loam of the Atlantic Coast section. In such material the 
charges must be heavy and must be skillfully placed to produce the perfect results shown. With 
proper care the excavation is satisfactory and the sides more even and true than in clay soils. 

(Charleston, S. C.) 



72 



and along roads, ponds, canals for drainage or boats, stream channels and 
similar cuts for any purpose can be blasted out. 

This book explains the possibilities of blasting and makes clear the 
basis on which choice of a method for your work should rest. It shows how 
to plan and to lay out drainage systems, and how to construct open ditches to 
the best advantage. Other methods than blasting are recommended frankly 
when conditions and purposes are such that can be used to the best advantage. 

Conditions Demanding Drainage 

Two classes of farm land should be drained. One is the usual swamp land 
where the ground is saturated with water or at least is too wet for the growth 
of cultivated plants. The other class is land now cultivated, but which at 
some part of the year carries excess water. 

The wet or damp lands may be merely low spots in fields, or may be entire 
valleys. Low spots often can be dried by cutting a ditch through rims of higher 
ground surrounding. If the wet condition is caused by overflow from streams, 
the stream channels should be deepened or widened till they carry all the water. 
If seepage from springs on the land or above it causes the trouble, a ditch cut 
across the flow of the seepage water will be the proper remedy. If the water-table 
is too high, a big open drain may gather and carry away the surplus, 
lowering the surface of the ground water to where it will not interfere with 
roots. 

On account of the matter of moisture storage, as well as on account of 
general fertility, all land which is cultivated should be drained thoroughly of 
excess water. It is not enough to reduce the surplus to a point where meadow 
grass will grow; the drainage must be sufficient to dry off the ground soon 
after each rain and soon in the spring. 

Roads always must be well drained if they are to remain solid and hold 
their shape in wet weather. Crooked streams should be straightened, to pre- 
vent cutting of the banks and overflowing, and ditches and streams too shallow 
or small to carry the volume of water present should be deepened or widened. 
Swamp conditions are a menace to health, breeding mosquitoes and their at- 
tending diseases. It often pays to drain lowlands where water stagnates, from 
the standpoint of health and comfort alone, when they are worthless for any 
agricultural purpose. 

The Value of Drainage 

Good drainage not only removes surplus water but actually helps to store 
moisture against dry weather. When soil is choked with water, deep rooting 
of plants or trees is impossible, and the soil processes which make available the 
plant food are hindered or altogether prevented. It is the absence of air al- 
most as much as the presence of the water that does the damage. The better 
land is drained to a proper depth in each case, the finer and more mellow and 
crumbling it will be, and the more of useful moisture it will hold in the summer. 

Swamp land usually is very fertile when the excess water is removed, and will 
grow wonderful crops. It contains a rich supply of plant food. Such land 
must be aerated — drained — and limed before its fertility can be used. 

The direct loss of income from the idle acres in swamps can be figured by 
anyone. But this is not the only loss. There is the decreased net profit from 
other land that is farmed under the same ownership. The swamp land costs 
interest on its purchase price and taxes every year. This cost must be paid 
by the productive acres. 

73 





Two pictures that tell a story of swamp grass damming up a stream, which backs up and floods a 
field, ruining the hay, or corn or any other crop which may happen to be there. To dig out by hand 
or plow out such a clogged stream-bed is difficult and expensive, but to blast it out is the work of one 
man for an hour or so, at a comparatively small cost. (Mud Lick Farm, Julian, Center Co., Pa.) 



74 




Winding streams cut up and waste much land. They change their courses every year or so, tear 
away the banks at the curves, gouge out deep holes and build up sand bars. They occupy many 
times the area they would if straight, and practically ruin the soil which is worked over by the water. 
(Mud Lick Farm, Julian, Center Co., Pa.) 

There is another feature of the matter that ordinarily is overlooked. This 
is the black eye which the farm is given by a ragged-looking piece of swamp 
land touching the clean acres. Whether the farm is on the market or is to be 
kept as a home, the waste lands cut down its value and damage its reputation 
among all who see it, including the stranger passing by, the neighbors over the 
fences and the man who lives on it. 

It is a well-known fact that malaria disappears when mosquito bites are 
eliminated, and that the mosquitoes can be eliminated by draining the swamps. 




The excavation done by a single line of charges of explosive properly placed in watersoaked clay 
soil is remarkable. The ditch resulting sometimes is two-thirds as deep as it is wide at the top. The 
bottom is U-shaped. 

75 



In the lowland sections of the country this has been done with great success. 
Even in the flat lands joining the ocean where tide water sometimes washes in 
over land and makes ponds, the opening out of channels has drained away the 
water and killed off the mosquitoes. 

Other enemies that breed and lurk in swamps are weeds and predatory 
animals. The seed weeds in the swamps pollute all the surrounding land, and 
the cleaning up of the swamp is a favor and a benefit to the entire neighborhood. 

Horses and cattle often get mired into the soft mud and are unable to get 
out without help. They may stick there and starve if not discovered and pulled 
out, or they may break a leg, or sprain themselves in their struggles. 

One of the meanest things a farmer has to do is to haul loads of hay, grain, 
manure or fertilizer through a swampy place in the field. The remedy is to 
open a ditch through the center, after which the soft ground will harden up 
and the ditch can be bridged. 

But not all wet land should be or can be drained. In general whether 
it will pay to drain or not will depend on how cheaply the job can be done, 
though this is such an indefinite rule that it is not of much value. Many a 
drainage job that can be done for $50 to $75 will add $100 to $200 to the 
value of a property. From a financial standpoint, a man is not justified in 
spending more money than the crops that can be grown will return in a reason- 
able number of years, though other considerations may make it wise to spend 



The Essentials of Successful Ditching 

It is well to have a clear idea of what to require of a ditch before attempt- 
ing to complete the plans for it. 

The successful drainage ditch 
should be straight, to give an even, 
swift flow of water without cutting 
out the banks or filling up the 
bottom. Its sides and bottom 
should be smooth and true, both to 
facilitate the flow and for appear- 
ance. It must be deep enough to 
put the water-table at a proper 
level. It must be wide enough to 
give the capacity required by the 
volume of water to be carried in 
flood times. The grade, of course, 
must be enough to carry the water 
away and to make the drainage 
action sure. 

The excavated material ought 
to be well scattered and spread 
evenly over the surrounding land, 
without leaving a ridge or dyke 
along the sides of the ditch. When 
this material is piled up along the 

ditch it takes up ground space and One of the best demonstrations of the value and 

ar f e a<! a Jam f nr c, ir farp warpr success of the blasting of ditches is in cutting a large 

acts as a aam ror surrace water channel through difficult ground for a short distance, 

and compacts the Subsoil beneath as this picture shows. One man can do the work in 

. \ . . . 11- a c o u P'e of hours. The expense is not to be com- 

by its weight, making the drainage pared to the cost of cutting the same ditch by plow- 

of the fields much slower. Finally, ing ' hand shoveling or machine w & ey C reek, Pa.) 

76 




the ditch in respect to cost, time and men needed for construction, must come 
within the available limits. The cost must be low, the time of construction 
short, the men required few, and the work not unreasonably hard. Frequently 
if the ditching is to be done at all it must be by only two or three men in what 
practically amounts to spare time. 




The line of the ditch follows the line of the charges faithfully, making true curves and angles. It 
should be the policy to eliminate all twists and to make the ditch as straight as a string whenever 
possible. (Chester Co., Pa.) 



Nature of the Ground 

The reasons why land is wet are few. There may be a layer of ground a 
few inches or a few feet under the surface, holding the water from escaping 
downward. The topsoil itself may be of such a nature as to prevent water from 
percolating through it. The water may keep rising from springs, producing 
the condition called seepage or spouty land. Again, the water-table, or height 
of the surface of a nearby large stream or lake or bay, may be nearly up to 
the surface of the ground, or the stream or ditch carrying away the water may 
be too small or too high at its mouth. 

The nature of the ground must be considered in deciding on the method 
of ditching. Sand, for instance, is easiest to handle by some methods, and 
hardest by others. Dry ground handles cheapest in some ways and most 
expensively in others. In ditching you are likely to encounter hardpan, gravel 
of all sizes, both loose and in solid beds, and every kind of mixture of these 
materials. Each of these conditions calls for its own sort of treatment. 

77 





A ditch blasted through very dry ground without any side cutting. The result is not altogether 
a success, since the excavation is reduced in amount and is incomplete, and the cost is high. The 
soil is coarse sandy loam with much clay beneath. The blasting would have been much more suc- 
cessful if the ground had been full of water and the sides of the ditch cut before the blasting was 
done. (Near Snow Hill, Md.) 




Heavy charging and skillful management will blast out a very good ditch through extremely dif- 
ficult ground. Here the soil was matted with green roots. Some of them are left projecting into the 
ditch, but most of them are broken off and thrown out. The excavation of earth was very complete, 
owing to its watersoaked condition. (Georgia.) 

78 



Choosing a Method of Draining 

The methods that are available for making ditches are: 
Shoveling by hand, 
Plowing, 

Trenching with machine equipped for excavating, 
Blasting. 

Each method has its place. In choosing a method many considerations 
enter into a wise decision. The purpose for which the ditch is made — whether 
open ditch or underdrain, canal for water or boats, and the like, must determine 
the character of the ditch. The kind of soil, the size of the ditch, the amount 




Note the projecting knobs of earth held by matted roots of trees and brush. Such irregularities 
in the sides of a ditch are not a disadvantage except in appearance in a ditch where the flow of water 
is heavy and swift. But when the volume of water is small and the fall slight the edges should be 
smooth and straight. 

and kind of obstructions, the time available before the job must be finished, the 
men that can be put on the job, the capital available for labor and equipment, the 
source of the water to be drained away, the height of the water-table, the use of 
the land to be drained, the amount of water to be carried and the fall of the land 
— all these factors have a bearing on the selection of the method of making a 
ditch. 

Tile Drains 

No open ditch through cultivated land should be considered when 
conditions are such as to make underdrains better, and when money is avail- 
able for constructing them. 

But in a great many places the nature of the ground or water flow is such 
as to require open ditches. In other places they are just as good as closed 
drains. For instance, through pasture land and woods an open ditch will do 
just as well as an underdrain and better where there is a spring or brook 
which overflows at times. In muck land closed drains are not practicable. 

Ditches for immediate laying of tile cannot be blasted out with satisfaction; 
the bottoms are left too soft to hold the pipe properly. If funds for tile drain- 
ing are not available immediately, an open ditch can be made by blasting 
which, after a couple of years, will be entirely satisfactory for tiling, though 

79 




Proper blasting will open a channel through thick brush and grass, though such a ditch will not 
measure nearly so much in the clear as though the land was clean and free from roots. You can blast 
channels for boats or for drainage through a marsh where the ground is under water. (Kentucky.) 

the earth required to refill the ditch will be scattered widely. Light blasting 
very often is desirable, however, to loosen hard ground in order to make dig- 
ging of tile ditches by other methods easier. 

Open Ditches 

Large ditches and canals, 1 5 feet wide or more, and miles in length, often 
justify the use of a floating dredge. Those who are interested in methods of 
trenching for underdrains, and in excavating machinery, floating dredges, 
ditching plows and the like, should get Farmers' Bulletin 698 of the U. S. 
Department of Agriculture. It goes into the subject in detail. 




An entirely successful ditch blasted through heavy, thick muck. Note that the watertable is very 
near the surface of the ground. The soil is not thin enough to cave in or float into the excavation, 
hence the blasting is at its best. (In Howachitto Swamps, Adams Co., Miss.) 

80 



When many stones, roots and 
stumps are present, a dredge, or in 
fact any excavating machinery, 
cannot be used to advantage or at 
all. Ditches less than 2 feet deep 
can be plowed out cheaply, using 
two or four horses hitched by means 
of a chain to a plow of some kind. 
Another implement that is effec- 
tive for making very shallow 
ditches is a scraper, either with 
or without wheels. A road machine 
or scraper is about as good as any. 
The trouble with these machines 
is that they will work little more 
than to a depth of a foot, and are 
expensive. Their advantages are 
that they scrape the dirt well back 
from the edge of the ditches and 
make an even, clean-looking job by 
machinery instead of by hand. 

When tile is to be laid in hand- 
dug trenches, begin the spade work 
in the bottom of a plow furrow. 
By running the plow twice in the 
same place you can make the fur- 
row nearly 1 2 inches deep. 
Blasting of ditches is discussed under a separate heading. 

Possibilities and Limits of Blasting 

The blasting method can be used for making almost any open ditches. 
A blasted ditch made with one line of charges usually is about twice as wide 




What can be done by blasting in sand. This big 
ditch was made with explosives near Pinellas, Florida. 
The conditions are about the most unfavorable under 
which it is possible to blast out ditches. Heavy charg- 
ing and electric firing were required here. 




Blasting makes the cleanest and smoothest job in sandy loam that is saturated with water nearly 
to the surface. Note how cleanly the edges of this ditch are cut. Also note that no excavated earth 
was thrown to the right of the ditch, in the picture. A strong wind carried it all over to the left side, 

81 



at the top as it is deep. The sides and bottom are fairly even. The dirt is 
spread out widely without leaving ridges down the sides. Ditches can be 
blasted successfully in clay, loams, gravel, thick muck, peat, and, in fact, every 
sort of earth except very thin muck and dry sand. Ditches can be blasted 
through sand when saturated with water. 

It is easier to state the limitations of the blasting method than its possi- 
bilities. As stated above, you cannot blast ditches through dry sand. Thin 
muck runs into the excavated channels. In any ground where there are many 
roots of trees or brush, the sides of the blasted ditch will be ragged unless the 
roots are cut beforehand along the sides. In blasting through heavy sod, the 
sod sometimes folds back without tearing loose, or else simply flops back down 
into the ditch — unless the edges are cut before the blast. 

These are the limitations of blasting, and there is a way to overcome each 
of them except that of thin muck. The fact is that the way explosives will 
cut out a narrow channel is really wonderful. Those who have not seen the 
blasting of a ditch can have no idea of the efficiency of the work of explosives 
for this purpose or of the clean and finished job they do. 

Explosives work to the best advantage when the ground is wet in fact 
in thin mud. It takes less explosive to throw out a required sized ditch, or the 
same amount of explosive will make a bigger ditch, when the ground is thoroughly 




A big ditch blasted through a swamp where the muck was almost too thin. The sides of the 
ditch moved in a little, but stopped as the water left them and they dried a little. Blasting is very 
effective in muck, so long as the material is not so thin that it moves in and closes the excavation 
later. (Gilliard's Lake outlet to Mississippi River, through Howachitto Swamp, Adams Co., Miss.) 

wet than when it is only damp or is dry. The blasting may be done with per- 
fect satisfaction through ground that is so soft that there is no footing for 
horses and no support for wheels. In fact, it can be done when the surface 
of the ground is under water. 

Excessively soft ground, stones, stumps and roots are the things that 
make ditching by hand or by machinery costly and difficult, if not impossible. 
But they interfere with blasting very little and raise the cost only slightly. 
Blasting of ditches can be done in dry ground of a heavy nature. The general 
rule is that the wetter the soil, down to the thin muck stage, the better and 
cheaper the blasted ditch. 

82 




It is possible to blast out a good ditch through almost pure sand, as this ditch shows, provided the 
ground is full of water and the operator understands his business well. 



About the smallest ditch it is worth while to blast is 1 yi feet deep and 
3^ feet wide. From this size up to 6 or 8 feet deep and 1 8 or more feet wide the 
use of explosives has advantages over almost any other method under 
favorable conditions. But in general the efficiency of the blasting method 
falls off after the depth is greater than 6 feet and the width greater than 1 8 
feet. For long ditches a floating dredge will be economical. Small ponds may 
be dug by blasting. 

In blasting ditches two or three men can do the work of a great many. 
They can accomplish in a day or two what would take them months to do 
by hand. 



Laying Out the Ditch 

The size or capacity of ditch required, the grades, the depth and the lines 
should receive careful attention. When there is considerable length of ditch 
or considerable acreage to be drained it is wise to employ a drainage engineer 
or a professional surveyor in getting the grades and in determining capacity. 
Except in very large operations the matter of depth and location of the lines 
of drains is largely one for farmers themselves to decide, because they know 
the requirements of the different soils and of farm operations, as well as 
have had the chance of observing the flow of flood water. 

The eye is not to be depended on in determining the fall of a piece of land 
that is nearly flat. Use a level. One way of using it is to drive a post at the 
upper side and fasten to this, by nailing or bolting, a crosspiece with a straight 
edge up. Then lay a level on the straight edge and make it absolutely level. 
The crosspiece should point directly toward the lower side of the piece of land 

83 




In big drainage projects where large canals must be made the blasting method otten proves 
economical. There is no doubt that explosives will do the excavating, as this picture shows. Labor 
cost and complications are reduced to a minimum on account of the few men and short time required 
for the blasting. 

to be drained, where a helper must stand, holding a marker which he raises or 
lowers on a pole. Sight over the straight edge and have him elevate the marker 
till it is on a true level with your crosspiece. The difference between your dis- 
tance down to normal ground surface or normal water surface, and his, will be 
the fall. 




This ditch is a good instance of the speed and efficiency of the blasting of ditches. Three men 
made it complete, as the picture shows— 1000 feet long— in 5 days. About 400 pounds of explosive 
was used. Much cutting of roots and sod was required. (The Hart E. Hutchens Co., New Bnta'n, 
Conn.) 

84 



An "A" frame or any other support for the level will do if it will hold the 
level steady. Sights for attaching to the level can be bought of almost any 
hardware store. They are as accurate as rifle sights. Tripods for holding the 
level also are made and can be had at most hardware stores. The plain level is 
not very accurate. If you do not use sights, repeat the sighting two or three 
times to make certain of the finding. 

A fall of one inch to each hundred feet is enough to carry off excess water 

from a field 




Grade, Fall and 
Line of Ditch 



in most cases. 
This is for 
straight 
ditches. If the 
ditch line is 
to swing here and there, an inch 
of fall is hardly a sufficient allow- 
ance. 

The appearance of grade is 
deceiving. Few pieces of ground 
are so flat they cannot be drained. 
Watch the land when it is flooded 
and the water is going down. Set 
some stakes then to indicate its 
level and its channels. If a small 
stream flows through the land, the 
line of sight should not follow its 
wandering course. The total fall 
should be determined from just two 
positions — one where the stream 
enters and one where it leaves. 

The flow of the flood water is 
a good guide in locating the proper 
line for a ditch. This is the nat- 
ural line of drainage. If nothing 
else interferes, place the ditch in 
this position. The idea is to have 
it as near as possible to a straight line and as short as possible. But avoid cutting 
fields with open ditches when possible. 

The one important factor to consider in determining how deep a ditch 

should be is the proper height of the water-table in the ground. This is the 

level of the water that will stand in a well or hole dug in the 

wettest part of the field. The water should be at least 4 or 

Determining 5 feet below the surface in ordinary heavy loam or clay, and 

Ditch Depth 1 to V/i feet in muck. 

The deeper a ditch is the farther and more thoroughly it 
will drain land. Your calculations as to how far you can rely 
on one ditch to gather water and to effect the drainage of ground must be based 
on this matter of the depth of the ditch. The nature of the ground has a good 
deal to do with it, particularly with the rapidity of the drainage. A loose, 
open gravel will drain out nicely in a few days, and a tight stiff clay will take 
weeks. Naturally the ditches should be closer together in the clay than in the 
gravel. Other soils can be judged from these. 

The depth must not be more than the water-level at the mouth of the 

85 



Part of a half mile of ditch blasted out com- 
plete, with no work in preparation or finishing ground. 
The ground was full of water, and transmitted deto- 
nation was made use of to fire the charges in about 
200-foot sections. Note that the line of the ditch is 
true, the edges fairly even and smooth, and the earth 
well scattered. 




The first shot (of 12 charges) of a ditching operation. Note particularly how abrupt and clean- 
cut the end is. The last charge lifted its load fully and cleaned out the ditch in good shape. The 
next one placed beyond will continue the excavation just as well. (Mud Lick Farm, Julian, Center 
Co.. Pa.) 

ditch or drain. This is a governing 
factor in many places. When a 
ditch empties in a stream you often 
can carry the channel farther down 
and secure a lower level if it is 
needed; or the stream itself may 
be deepened. 

The water carrying capacity of 
a ditch is most largely governed 

by its width. 

Often the nar- 
Determining rowest ditch 

Width of Ditch that can be 

made will 

have more 
capacity than is needed to carry all 
the water there is. The bottom 
should not be wide, but should be 
narrow, almost like a broad V, 
because the amount of water to be 
carried at low water stage is small 
and it should be confined closer to 
make it flow better. In flood times 
the water will rise higher and will 
make a broader stream. 

Where large swamps are to be 
drained, or the flow from larger 




This ditch is S feet wide and 3 feet deep. It 
was blasted out with one row of charges placed 18 
inches apart, each charge consisting of one cartridge 
of powder. About 100 feet of the ditch was excavated 
at each explosion. 



springs is to be carried away, a ditch of minimum width sometimes is not big 
enough. If you can calculate the volume of water to be carried away, you 
then can figure the correct width for your ditch. Measure the flow per minute 
in cubic feet at some outlet. Or measure the amount of standing water by 



getting its depth and extent. Provide ditch enough to pass the volume 
present in the required time. In any case the ditch should be big enough to 
clear away the water of a 2 or 3 days' rain shortly after it stops coming down, 
and to take care of spring floods. 



How to Make Ditches by Blasting 




Ditches are blasted by loading 
suitable charges in holes made in a 
row or line. Each 
charge of explo- 
Description of sive properly 
Blasted Ditch placed for ditch 
blasting will 
blow out, rough- 
ly stated, a crater which is half to 
three-quarters as deep as it is wide. 
Nearly all the dirt is thrown out. 
Most of it is lifted to a height of 
about 200 feet in the air, requiring 
some seconds before it returns to 
the ground. 

The sides and bottom of 
blasted ditches have 6 to 1 2 inches 
of loose dirt, which can be left 
where it is if the ditch is big enough 
in the clear, or can be taken out 
easily and cheaply by shoveling or 




In these ditches the excavation of earth was satisfactory, but the number ^of roots ; was ^so great 
that the result as a whole is not what it should be. No side-cutting was done before blastimj. If 
thlre hid been, the resulting ditch would have been smooth, straight and deep. In Mastmg &***& 
brush and timber, the longf sharp shovel blade, the hay-knife and the axe are necessary tools. 
(S. Chester Coursey, Hayden, Md.) 

87 



with light horse scrapers if a larger ditch is wanted. Good blasting practice 
will so load the charges that the ditch as cleaned out by the blast will be big 
enough in the clear and will require very little, if any, hand finishing. 

Firing Charges 

One of the first things that must be considered when planning to make a 
ditch by blasting is the method of firing the charges of explosive. Most of the 
rest of the operation hinges on the firing so much that this matter must be de- 
termined before even buying the explosive. 

The standard practice is to fire all charges electrically, as will be described 
immediately following. This method is sure in results under any conditions. 
Ordinary cap-and-fuse firing cannot be used successfully in ditching, except by 
the transmitted detonation method in which the center charge only is set off 
by a cap, the rest being fired by shock transmitted through the ground. This 
method is fully explained on pages 89 to 92. 

General Method of Firing 

Ditches can be blasted through any sort of ground except dry sand when 
the charges are fired in this way. The procedure is as follows: 

The charges are prepared for loading, with electric blasting caps, in the 
manner described on pages 1 50 and 151. Prime each charge. Holes are made in 
the ground on the ditch line and the charges are loaded as described in follow 
ing pages. 




Typical loading of ditch blast for straight electrical firing ol all charges for 3) 2' x T ditch. 



-'-Air : - ■ ■■■- ;,-M : li^ 



The holes or charges should be spaced 30 to 40 inches, and where very 
heavy charges are used, as much as 50 or 60 inches apart. They must 
be close enough together so that all the earth between each two will be thrown 
out clean, leaving no ridges in the bottom of ditch. Thirty inches ought to be 
close enough under any conditions of soil and size of charge. The only way of 
determining definitely just how far apart the charges should be is to make test 
shots, as suggested on page 98, in the discussion of amount of explosive required 
for charges. As many charges should be loaded as your electric current can 
fire. 

The actual firing is done by connecting the wires of all the charges and send- 
ing an electric current through them. An electric blasting machine should be used 
to supply current, though power or light current can be used. A full discussion 
of the details of how to connect wires and to fire, is contained in the special 
chapter on the subject in the latter part of this bulletin. 

You can fire as many charges as your blasting machine will handle. The 
machines are made in different sizes, to fire 3 to 1 50 charges at once. Procure 
a large machine if you have miles of ditch to blast, but if you have only a few 
hundred yards, a 30-charge machine is big enough. 



The proper explosive for blasting ditches by this method depends somewhat 
on the soil. In all clay and heavy soils use 20% ammonia dynamite, and for 
large ditches use 30% or 40' ammonia dynamite except when the work is under 
water. (See page 154.) In blasting ditches in wet sand or other light ground 
use 50 % nitroglycerin dynamite. Where charges must remain under water more 
than half an hour, use nitroglycerin explosives only, for ammonia explosives will 
deteriorate if soaked for excessive periods of time. It is well to use a low- 
freezing grade of the explosive at any time of the year, since this guards against 
chilling, and insures a more thorough detonation of the explosive by the blasting 
cap. 

Electric blasting caps, connecting wire, leading wire and blasting machine 
with the other tools needed for loading, are the supplies demanded for ditch 
blasting by this method. 

Depth for holes, amount of explosives per charge and many other details 
of the loading are discussed on pages 95 and 97. 

Transmitted Firing 

When the ditch is to be blasted through ground that is saturated with 
water, the method of transmitted firing often can be used to advantage. In 
order to insure its complete and unquestioned success, the water must cover 
the charges and had better rise in the holes nearly to the surface of the ground. 

Under such conditions transmitted detonation can be expected to succeed 
even in sandy ground and gravel. It is in muck and clay fully saturated with 
water that the method is most successful. 



•*§&. 




Showing typical loading of transmitted detonation ditch blast--fuse firing-tor 3J^' x 7' ditch. 

Transmitted firing is made possible by the fact that high explosives can 
be fired by shock (as by that given by a cap, for instance). Under the conditions 
of soil described above and of proper loading, the shock of the explosion of one 
charge will travel through the ground and water with enough force to fire the 
next charge, and so on down the line. So rapidly does this take place that in 
a line of charges hundreds of feet long you cannot see any difference in time 
between the middle and end explosions. 

If cartridges of explosive are laid on a plank a foot apart and one of them is 
fired with a cap and fuse or otherwise, the others likely will be exploded by the 
influence projected through the air. In actual ditching work the shock of one 

89 



charge cannot be depended on to travel through the ground strongly enough 
to bring about full and complete detonation more than a couple of feet. 

The usual distance apart that is best for charges to be fired by transmitted 
detonation is 15 to 20 inches. The exact distance in any particular soil at any 
time must be determined by test shots. Try a shot of 8 or 10 charges (of the 
amount of dynamite and at the depth of loading required, as explained on pages 
97 and 98, spaced 12, 15, 18. 20, 22, and 26 inches apart. 

Careful observation of the blast resulting will show the point beyond which 
charges fail to explode or explode weakly. The cor- 
rect spacing of charges, to insure full detonation, will 
Spacing of Charges be about two-thirds of this limit. 

One charge may fire another at a greater dis- 
tance than is economical, because it merely may ex- 
plode it weakly, without developing anything like the full force and speed. 
And on top of that, each weaker explosion sends a still weaker one on to the 
next charge, till a point is reached a few charges away where the shock trans- 
mitted is not enough to bring about firing at all. 

This weakening of the transmitted shock is important, because the strength 
of an explosion of dynamite depends on the severity of the shock which fires it. 
For illustration, and not that these figures bear any relation to the true amount 
of force, if the first charge, the one fired with a cap, gives off 1 pounds of energy 
in the form of a shock, and this 1 pounds is diminished to 8 pounds by the time 
it reaches the next charge, this second charge will not detonate with quite 10 
pounds of shock energy. ( It may have only 9 or 8. And in turn, the shock 
energy from it will be diminished to 6 or 7 on reaching the third charge. If the 
particular kind of explosive used requires a full 6 pounds of shock to detonate 
it completely, the transmitted method of firing is going to fail. Even of those 
charges which do explode, half will give much less than their full force. 

Water is not elastic, but air is, and dry soil is and absorbs shock because 
it contains a good deal of air. The gases of an explosion drive water-soaked 




When roots and sod are not cut along the sides of the ditch before the blasting, the edges are 
never as smooth and as straight as with cutting. An effort was made to trim this ditch up after the 
blast. It carries water about as well, but it doesn't look to be as good. (In Miller Drainage District, 
Marion Co., Oregon.) 

90 



ground as a steel rod can be driven by a hammer. In it there is but little 
"give," hence the shock travels with a minimum of loss in force. In dry 
ground the air cushions the blow of the gases and eases them to a standstill 
within a short distance. Clay is more solid than sand, and this explains why 
transmitted detonation works better in heavy soils than in light ones. 

The nature of the ground and the amount of water present therefore 
largely govern the spacing of charges, though a large charge of course will throw 
a shock slightly farther than a small one. 

As will be seen from foregoing named facts, the effects of lack of water 
and of light, spongy or sandy ground, can be counteracted somewhat by set- 
ting charges closer together. When necessary it is practicable to put them 
only a foot apart. To put them closer, however, is not practicable, for it costs 
too much. On the other hand, when the charges are heavier than ordinary — 
say of two cartridges or more — in wet, heavy ground, they may be spaced up to 
26 inches apart with satisfaction. 

Temperature influences transmitted detonation only by reason of the fact 
that explosives are less sensitive to shock, and harder to fire when cold than 
when warm. All grades explode easiest when at a tempera- 
ture of 70 to 80 degrees. Straight nitroglycerin dynamite 
Temperature must be used at a temperature of higher than 50 degrees, 
of Ground It is not well, for many reasons, to attempt to fire too many 

charges at once. Several hundred can be fired successfully 
sometimes, but the usual limit had better be 50 to 60. 

When the nature of the ground, amount of water present or temperature are 
not of the best for securing transmitted detonation, matters may sometimes be 
helped by taking advantage of the fact that blasting caps are much more sen- 
sitive to shock than the explosive itself. Place a common blasting cap, without 
a fuse, but with the open end filled with tallow, every 25 to 50 feet. These 
caps may help to restore the diminished force of explosion, making satisfactory 
detonation extend much farther than it would without them. 




A ditch 10 feet wide and 5 feet deep through newly cleared land. The extra width of the exca- 
vation helped to tear entirely loose and throw out stumps and roots, leaving the edges comparatively 
clean of projecting roots. Under such conditions finishing the ditch after blasting is better than to 
try to cut the edges before. (Paragould, Ark.) 

91 



Stones, roots and old logs interfere with transmitted detonation. When 
these are located in the line of the ditch it is necessary to fire charges on both 
sides of them as at the beginning. Pay careful attention to changes in soil as 
you work along the ditch line. It may be necessary to shorten the spacing, 
or, again, it may be possible to lengthen it and save money. 

The firing of the line of charges by the transmitted detonation method is 

done by loading the required number of charges without priming or with caps 

and no fuse as described above, all except the center charge 

Prime Center of the row. In it place a double charge of explosive, or at 

Charge least an extra cartridge of explosive, primed with cap and fuse 

or with electric blasting cap. Fire this charge in the usual way. 

Sometimes an electric blasting cap placed at each end as well as at the 

middle of the line will fire difficult charges successfully. Once in a while the 

electric blasting caps may be needed even closer — say every 3 to 5 charges. 

The proper explosive for transmitted firing ditch blast- 
The Explosive ing is nitroglycerin dynamite of 50% strength— either regular 
to Use or low-freezing. The 20% strength dynamites recom- 

mended for electrical firing cannot be used at all under this 
method, because they are not sensitive enough. 

Summary of Firing Facts 

Transmitted firing requires only the explosive itself, and a cap and some 
fuse for each couple of hundred feet of ditch, while electrical firing requires 
wiring, an electric blasting cap for each charge and a blasting machine or other 
source of current. This advantage of the former method very often is offset, 
however, by the fact that it requires nearly twice as many holes as electric 
firing. It is easier to load two cartridges in one hole than to make two holes. In 
addition, electric firing always can be depended on for the desired results, while 
transmitted firing will succeed only when the ground is full of water. As for 
quantity of explosive required by each method to excavate any certain ditch 
where either can be used: In theory the two methods require about the same. 
In practice, however, more will be used in transmitted firing, unless the work is 
done very skillfully. The saving in the use of this method comes largely from 
a saving of electric blasting caps and time, and the need for little equipment. 

Preparation of Ground and Loading 

During the early days of ditch blasting, before experiments had standard- 
ized practices, much objection was taken to the ragged edges of ditches blasted 
through sod and through brush and woods. The sod would 
not tear loose and fly away from the ditch. It would either 
Cutting Roots fold back and make a ridge along the ditch, or it would flop 
and Sod back into the ditch after the dirt beneath had blown out. 

The remedy is to cut the sod and roots along the edges of 
ditch before blasting. 
When there is sod, two furrows should be plowed along the ditch line — 
one at each edge. Another plan is to cut along the sides of the ditch-to-be with 
a spade, axe or hay knife. In case the line of the ditch runs past trees, or 
through brush or forest land, the roots should be cut on both sides the ditch. 
An axe is needed for the big roots. Where there are many roots the ground 
should be cut 1 8 inches deep. 

Make the cut at the angle the side of the ditch should have, say about 45 
degrees. The blast will clean out the dirt to the cuts and will leave the wall 
on the outside firm and intact. Cutting the edges of the ditch saves trouble 

92 



and work after blasting. It insures that the sides and edges of the ditch will 
be as straight as though the ditch was shoveled by hand or plowed. But it 

should not be understood that 
ditches cannot be blasted without 
cutting the ground. Except through 
extremely heavy sod and roots, 
explosives used alone will clean out 
good channels when loading and 
firing are done properly. The cut- 
ting of the edges simply makes a 
smoother, more complete job. 

The charges should be placed 
along the center line of the pro- 
posed ditch, except where the 
ground is harder, 
or higher at one 
Locating Line side than at the 
For Holes other, when they 

should be placed 
6 to 12 inches 
from the center toward that side. 
The eye is not capable of keeping 
the line of charges true. Stretch a 
string where they should go. In 
making the holes the man should 
have a measuring stick to space 
them accurately. Guesswork on 
this point is likely to be expensive. 
Make the holes straight down 
into the ground. 

It is much easier to make holes 
in soggy ground than in dry ground. In fact, it is almost impossible to sledge 
down a bar in some dry ground. When there are no stones, a soil auger often is 
of advantage, though the bar and sledge are hard to beat for speed and re- 
sults. Modification of the up-and-down position of the cartridges or charges 




A typical instance of what results from an attempt 
to blast a ditch through heavy sod without first cutting 
the sides. The sod breaks loose in the middle of the 
ditch and either folds back without tearing loose or 
falls back into the ditch after the dirt beneath it has 
been swept away. Such ground should be thoroughly 
watersoaked and the edges of the ditch cut with 
shovels or hay-knife, or at least by plowing furrows. 
(Virginia.) 




^-^^S- 



%mt ■# •.. ■•-jut* . W»r>i. 



Typical loading for deepening ditch with bottom of mud — electrical firing of center charge for trans- 
mitted detonation. 

is desirable only when you are deepening ditches already made, with bottoms 
of thin mud or thick muck. In such material you need punch no holes. Just 
push the cartridges into place down in the mud with your hand and place them in 
a horizontal position lengthways of the ditch. 

93 



If you have a windy day for 
the blasting, with the air drawing 
strongly across the ] 



Preventing Dirt 
Falling into Ditch 



iine of the 
ditch, you 
will be sur- 
prised to see 
how far the 
falling dirt 



will be car- 
ried away from the ditch during 
the few seconds it is in the air. On 
a quiet day, 6 to 1 2 inches of dirt 
will fall back into the ditch. On 
a windy day your finished ditch 
will be several inches deeper and 
wider than on a calm day. Do not 
take from this that a windy day is 
demanded for satisfactory results. 
The force of the blast spreads and 
scatters all but a little of the dirt. 
The wind merely helps. 

When water covers the charges, 
be sure to make the primed car- 
tridges, and the cap and fuse, 
waterproof with tallow or paraffine 
at points where they join. Tar and 
thin lubricating grease are very 
poor materials for waterproofing. 




An explosion throws the earth so high that the 
slight additional depth or height of sides met with in 
deepening a ditch does not interfere materially with 
the excavating action of the blast. Probably a little 
dirt is caught and rolled back by the side walls, but 
the percentage of the total lifted is small. 



When water covers the charges you should arrange to 
Waterproofing load them and to fire them quickly. A good plan is to make 
Charges all the holes for one section, then prepare the charges, as to 

priming and waterproofing and distributing them along the 
line. Quickly test each hole for fallen stones, caved-in dirt, and push the 
charges to the bottoms of the holes. It is best to limit their soaking to a 
half hour. The explosive is likely to weaken if left too long. 

If the holes cave in soon after the bar is withdrawn, do not attempt to 
load and blast long sections at a time. In loose gravel and sand, especially 
where water covers the surface or nearly so, you will have trouble getting the 
charges down to the bottoms of holes. The best plan is to get a tin tube 
about 1 */2 inches in diameter and sink it in the hole over the bar. The 
explosive then can be loaded without trouble when the bar is withdrawn. 

Generally speaking, a ditch charge should be tamped slightly. The more 
tamping you use the broader your ditch will be in propor- 
tion to its depth. If you want a narrow ditch you must 
Tamping Ditch let the gases rip their way upward easily. In dry or damp 
Charges ground, fill the hole about half full and tamp well. When 

water rises high in the hole, use no tamping at all, except 
to tramp shut the upper 6 inches. 
The ground had better be warm for ditch blasting. If it is cold you must 
load and fire the charges quickly, to prevent chilling of the explosive. A light 



^4 



crust of frozen ground makes little difference when charges are handled 
properly; more than % to ¥2 mcn wili interfere seriously. 

Regulating Depth and Width 

The dirt will clean out 6 to 8 inches deeper than the bottom end of the 
charges when conditions are normal. Explosives work more efficiently in ditch 

blasting when they are placed as shallow as possible. 

When the holes are too deep an excessive amount of 
Depth for Charges explosive is required. A layer of hardpan or cemented 

gravel in the ground to be removed requires slightly 

deeper placing than soft ground. The rule for the 
usual job is to place the charges within 6 inches of the bottom depth desired, 
and for large ditches and heavy charges within 10 or 12 inches of the desired 
depth. The exact depth may be ascertained by trial shots. 

The greatest depth it is practicable to blast at one shot is about 6 feet. 
If a deeper ditch is wanted, blast a second time in the bottom of the first ex- 
cavation. (See table on page 98 for depths for charges.) The blasting out of 
very large canals should proceed along these lines. They involve no principles 
not explained for the making of small ditches. 




A channel 35 feet wide and 6 feet deep that was excavated by blasting. The water has smoothed 
the sides a little, but in the main the big ditch looks in the picture as it looked after the blast which 
opened it. The cost of such ditching can be figured accurately in advance when dimensions are known, 
the kind of soil and its condition considered, and the cost of explosions at hand. (Athens, Ga.) 

One line or row of charges frequently will make a ditch up to 10 feet wide 
and 6 feet deep. To make wider ditches use 2 or more rows. 

Usually 2 rows of charges will be needed for ditches between 8 and 12 feet 
wide if less than 4 to 6 feet deep, and 3 rows for ditches 12 
to 1 8 feet wide. 
Wide Ditches The lines or rows of charges should be placed about 4 

feet apart, except where the charges consist of more than 4 
cartridges and are close together in the rows on account of 
transmitted detonation, when the rows may be as much as 6 feet apart. In 
blasting out very wide and shallow ditches or canals, it sometimes is of ad- 
vantage to load 2 rows with light charges rather than to attempt to blast out 

95 




How to deepen ditch by a second blast in the bottom of a first excavation. 




Half cartridge loading for very small ditch. 



Single-row loading for large ditch — if larger ones are 
needed, more rows of charges. 
% 



the ditch to the required width with one row heavily loaded. The heavy 
charges might dig deeper than required. (See table on page 98.) 

Invariably all the rows should be fired together. This, of course, is ac- 
complished when the electric method of firing is used. When using the trans- 
mitted detonation method, put in extra charges between the rows at the center 
charges, and then fire one — usually the center charge of the middle row — with 
a cap and fuse. All these center charges and extra charges should be heavier 
than usual. Put in an extra cartridge, at least. A still better way with trans- 
mitted detonation is to fire the center charges of all the rows together electrically. 




A pond excavated entirely by blasting. Several rows of charges were loaded and fired simul- 
taneously. The wind carried the earth to one side, forcing it to fall on adjoining ground instead of 
back into the hole blown out. ( H. E. Ellis, Ashland, N. J. ) 

Amount of Explosive Required 

Before giving tables of the average amount of explosive required for vari- 
ous sized ditches, it is well to describe a few typical examples of ditches that 
have been blasted, of which records were kept. 

In a clay soil, with water rising almost to the surface of the ground in the 

holes punched for charges, charges of one cartridge cf straight 

nitroglycerin explosive placed 18 inches apart and 30 inches 

Examples deep blew out a ditch 4 feet deep, 3 feet wide at the bottom and 

7 feet wide at the top. 

In a similar soil, with less gravel, charges of one-half cartridge 
of straight nitroglycerin explosive placed 15 inches apart and 18 
inches deep made a ditch 2} o feet deep and 5 feet wide. At another point in 
the same field, on the same day, charges of 2 cartridges (one pound of same ex- 
plosive), placed 30 inches deep and 24 inches apart, made a ditch 9 feet wide 
and 4 feet deep. 

In loam ground, too dry for successful transmitted detonation but still 
somewhat damp, charges of 2} 2 cartridges placed 2} A, feet deep and 3 feet apart, 
and fired electrically, cut a ditch 4 feet deep, 8 feet wide at the top and 2 feet 
wide at the bottom. 

Through a thicket with brush and small trees measuring 1 to 3 inches in 
diameter, in heavy pure loam well soaked with water, charges of 2 cartridges of 

97 



straight nitroglycerin dynamite placed 22 inches apart and 3 to V/i feet deep 
made a ditch 4 feet wide at the bottom. The ditch was loaded too heavy. 
Charges of 1^2 cartridges would have been better. 

In very wet and miry clay, a ditch 20 feet wide at the top, 1 2 feet wide at 
the bottom and 6 feet deep was blasted with 3 rows of charges of straight nitro- 
glycerin explosive. All the charges were spaced 20 inches apart in the rows. 
The charges in the middle row were \ x /i to '34 cartridges, varying a little on 
account of variations in the soil along the ditch. In the two outside rows 
the charges were one cartridge each. The rows were placed 4 feet apart. One 
section of the same ditch was cut out to a depth of nearly 8 feet by using Ijj A 
cartridges to the charge in the 2 outside rows, and 3 cartridges to the charge in 
the middle row. 

When the ground is fairly heavy and is full of water you can count on each 

pound of explosive properly placed to clean out 1^ to 2 cubic yards of earth. 

The variations from this rule, both ways, will be on 

account of the presence or absence of water, the nature 

Amount Excavated of the soil and the size of the ditch. A ditch made 

By One Pound of with a single line of charges (measuring, usually, 

Explosives 3 to 4 feet deep by 3 feet wide at bottom and 6 to 7 

feet wide at top), will give the highest efficiency, 

and when the conditions are very favorable will show 

even a little more than 2 cubic yards per pound of explosive used. 

As the amount of excavation in one body increases, the efficiency of each 
pound of explosive will fall off somewhat. In very large ditches that are wet 
you will get out only 1^ cubic yards per pound of powder. In dry ground 
blasting, particularly if the ground is light, \ x ± or even one cubic yard per 
pound will be the average. 

Number of Half -Pound Cartridges of Explosive Required per Charge for 
Blasting Ditches 



Depth 


Derjth 


Amount Charge 


Amount Charge 


Ditch 


Hole 


Transmitted Detonation 


Electric Firing 


2 ft. 


1^2 ft. 


}/2 cartridge 


J 2 cartridge 


2y 2 h. 


2 ft. 


^<£ cartridge 


1 cartridge 


3 ft. 


2^ ft. 


1 cartridge 


134 cartridges 


4 ft. 


334 ft. 


IK cartridges 


7S/l cartridges 


5 ft. 


4M ft. 


2 cartridges 


33/^ cartridges 


6 ft. 


5 ft. 


2}/2 cartridges 


5 cartridges 



The width of the ditch can be calculated by doubling the figure for the 
depth in case of a single row of charges, or in the case of more than one row, 
by adding to the figure for double the depth the distance between the rows 
of charges. 

The table given above is correct for average conditions. Since variations in 
soils, temperature and other factors make necessary varying loading, the 
figures here should be used as a guide for starting test shots. 

No ditches should be blasted without testing the loading thoroughly be- 
fore proceeding with much work. Blast small sections at a time, and vary the 
loading to suit the changes in the nature and condition of 
the ground you encounter along the ditch line. Clay, sand, 
Making muck, loam and gravel all require variations in depth of 

Test Loadings charge, amount of explosive and sometimes in spacing of 
charges. Proper tests will enable you to decrease the cost 
and to make a better ditch than otherwise would be possible. 

98 




Typical test loading to determine proper charges and placing of explosives for electrical firing. Note 
the variations in spacing between holes as well as in amount of explosives used. (See page 90. > 

Five to ten holes make a good test. This should be repeated several 

times. Vary the depth and spacing and the amount of charges. Remember 

that proper blasting will ma\e perfect ditches at low cost, and that the only 

final way of determining proper loading is to try it. Well-balanced charges 

will be so loaded and spaced that the gases will lift the full load of dirt without 

overlapping much and without skipping any ground between. Load just heavy 

enough to insure clean excavation without excessively high throwing of dirt. 

Making 3-foot holes in clay and gravel, preparing charges, loading and 

firing can be done by one man at the rate of 20 to 50 charges per hour. If 

there are many stones in the ground, or if the ground is 

hard, the work will go more slowly. Wet gravel makes slow 

Time Required work. Two or more men will get more done in proportion 

than one man. Under favorable conditions one man has 

blasted out 1,000 feet of ditch 3 feet deep in 12 hours. 

One man should be able to blast 350 to 450 feet of ditch per day through 

brushy ground; if the land is clean he can do more, though where ground is so 

dry as to cause trouble in making holes, the work will go slowly. 




A crew of ten men — eight laborers, one blaster and a boss — working at a big ditch. The em- 
ployment of so many men is not justified except for very long ditches, for the job lasts only a day or 
two. A good sized crew enables the blaster to place and to fire the charges quickly, which is an 
advantage when the holes fill with water and when the temperature is low. (Max Ostner, Diehl- 
stadt, Mo.) 

99 




exre/ns/o/v eA/? 



Ditch blasters should have a soil auger, 
two crowbars, a sledge, a couple of long- 
handled shovels and a cutting spade. One of 
the bars should be 4 or 5 feet long and should 
be constructed for driv- 
ing. The other should be 
Tools Required 6 or 7 feet long, and may 
be made of piping, with 
a solid sharp steel point 
welded in. It is for use as a churn drill, with- 
out sledging. A broomstick or a wooden rod 
about 1^2 inches in diameter, for pushing the 
charges down and tamping, and an axe to 
help cut roots, also are handy. Of course, 
boxes or baskets for carrying explosives, cap 
crimpers and the usual outfit for handling and 
loading explosives as described on pages 36 
and 37, will be required. 



>>t/A/CM BAK 



How to use pipe to make a punch bar 
or to extend an auger. 



Incidentals 

Large stumps, stones or other obstructions 

along in the line of the ditch require a little 

extra explosive. Stumps up to 6 inches through and boulders up to 18 

inches in diameter will be thrown out by the regular ditch charges. 

Steel bar for making 
holes. 




Soil auger — note 
long point. 



Above these sizes use extra loading, as follows: For each 6 inches of the diameter, 
use one cartridge of explosive. For stumps larger than 30 inches, use 3 to 4 




A good kind of crimper. 

cartridges for each foot of diameter. Put the extra explosive directly under the 
stump or stone. 




How to place charges under obstructions in the ditch line. 
100- 




tea'*.**?* 



Through heavy sod, as shown here, blasting cuts the sides somewhat irregularly unless the 
grass roots are first sliced with a shovel blade or hay-knife. This ditch is well opened and entirely 
successful, but a good many projecting chunks of sod are left sticking from the sides. 

Ditches blasted through ground that has a raw surface and no roots will 

require no finishing afterwards. The edges and sides should be fairly true and 
even and the dirt should be well scattered. There will be 
few or no ridges along the ditch. Even through sodded 

Finishing Ditch ground and through woods and brush, when the sides of 
the ditch have been cut before blasting, there will be little 
hand work needed. If no preparatory cutting is done, 

however, some shoveling to smooth the sides and some cutting to take out 

projecting roots and sod may be advisable. 




This ditch was blasted out on a still day, and most of the dirt fell straight back to the ground. 
But it was spread out so that only a little of it fell in the ditch. The few roots projecting into the 
excavation can be cut off with little trouble. It is the roots of sod and matted roots of smaller brush 
and trees which give the trouble in blasting and require cutting beforehand. (Robert Jemison, Bir- 
mingham, Ala.) 

!DI 



This work should be done right after the blast, before the water has a 
chance to compact the sides. If necessary, leave dams of unblasted sections 
3 or 4 feet long every few hundred feet in the ditch, to hold back the water 
long enough for finishing. They can be blasted out afterwards. An old axe 
or a sharp grubbing hoe or adz will cut the ends of roots easily. But all this 
work can be avoided and a better ditch result if you will do the cutting before 
the blasting. Large clods, pieces of stumps or roots and stones in the ditch 
channel after blasting should be thrown out without delay. 

It has been stated (page 79) that ditches for tile or pipe cannot be blasted 
out satisfactorily. The dirt can be loosened with light charges, however, and 
the shoveling or excavating by other means thereby made much easier. If the 
pipe is to be placed deeper than 4 feet, it is even practicable to blast a 3-foot 
or deeper ditch on top, leaving only a little more excavating to do in the bot- 
tom. One must bear in mind, however, that the blasting throws dirt too far 
away to be shoveled into cover piping. Loosening as explained above, how- 
ever, to make digging easier, does not throw the dirt away. 




Two post electric blasting machine- 
push down type. 



102 



Blasting Orchard Soil 



The blasting of soil for tillage purposes was first tried more than a generation 
ago. Since 1 900 the practice has become general in many sections of the country, 
particularly in those localities where orcharding is one of the main businesses. 

The experiences of individuals and of official investigators have not been 
uniformly successful, though some remarkable results have been secured. 
When the idea of blasting soil for tillage first was freely offered to the public 
through advertising and the editorial matter of farm papers, many unjustified 
and foolish claims were made for it, and a great many mistakes were made in 
the actual blasting. These claims and mistakes are to be regretted, because 
they led to barren or damaging results and to uncalled-for criticism of proper 
blasting. 

As a general statement of the proposition, it may be said that soil blasting 

is to be regarded largely as inten- 
sive tillage. Its benefits are de- 
rived from its physical breaking 
and mixing, opening and loosening 
of the soil, and show themselves in 
the form of better drainage, an in- 
creased supply of moisture in dry 
weather and better root penetra- 
tion, and because of these, in the 
greater fertility of the soil. 

The movement to blast soil 
was at first popularly called "deep 
plowing" or "plowing with dyna- 
mite," but most farmers have come 
to know that blasting soil is in no 
sense plowing it. Blasting will not 
replace ordinary plowing, nor can 
plowing be made to do the work of 
blasting. 

The whole matter of orchard 
tillage and feeding must be taken up 
when soil blasting for the benefit of 
trees is to be considered intelligently. 
Blasting is but one spoke in the 
wheel. Much of the misconcep- 
tion which exists to-day regarding 
the value and benefit of blasting 
orchard soil is due to failure in 
grasping this fact. 

The subject necessarily is a technical one, and this bulletin must deal with 
chemical and mechanical processes of the soil, using technical language to some 
extent. But as far as possible the matter is kept to broad general principles 
known and accepted by the great majority of agriculturists. The problem is 
to find out whether or not the kind of tillage which blasting gives will produce 
beneficial results, and produce them at a cost within the reach of commercial 
orcharding. 

103 




This is the kind of result produced by blasting 
ground when it is wet, and sometimes by using too- 
quick acting an explosive in moist ground. The soil 
may be left in a worse condition than before the blast. 
See page 131. 




This hole was blasted out when the ground was much drier than at the time the crater in the other 
picture was blown open. Instead of the sides of the crater packing, they loosened and crumbled. 
But even this ground is not as dry as it ought to be. Also a subsoil blast never should blow out a 
"hole." See page 131. 



What An Orchard Soil Must Do 

When attempting to form judgment of soil tillage by blasting or to explain 
it, we should have clearly before us what we want to do with the soil and what 
we expect the soil to do for trees. 

The purpose or idea of cultivation of orchards is to get profitable growth 
and yield from the trees. That is obvious. We want the greatest net profits 
possible under the conditions of each orchard. No one pursues a system of 
cultivation for the sake of the system itself, although the farmer or fruit grower 
does a great deal of tillage work rather blindly and without knowing just why 
he does it or understanding the soil processes he is dealing with. 

But it is clear that to make trees grow and yield to their maximum capacity, 
requires so far as the soil is concerned, enough water, sufficient of the right plant 
foods, and root anchorage and feeding space. These 3 essentials for growth are 
delivered to trees only by the soil, and the work of the soil consists in sup- 
plying them to the trees. It must be in condition to deliver them. 

The Soil Problems in Orchards 

Correct fundamental education in the principles of soil nature and man- 
agement is so universal nowadays that the primary facts regarding the growth 
of plants, and their feeding habits, need not be discussed in detail in this bul- 
letin. It is enough for the purpose to say that every 
The Plant Foods reader is presumed to accept the facts that the plant 
foods which have to be supplied are nitrogen, potash, 
phosphorus and lime. These are the only ones out of the 20 or more elements 
used by plants as food which run short in the soil, largely because they consti- 
tute the great bulk of the materials, aside from water, that are taken up by 
trees. The source of supply of these important elements are, on the one hand, 

104 



Drainage and 
Moisture Storage 



artificial fertilizers and manure, and on the other hand, the soil itself (though 
nitrogen is derived from the air by means of soil processes). 

The water problem is not less well defined and understood. To some extent 
it consists in draining away surplus water from wet places and swamps, and in 
making certain of the effective drainage of all land during winter, spring and 
rainy periods of summer. To a greater extent it is a 
matter of storing enough water for the use of the trees 
during the growing season. No orchardist questions the 
fact that the lack of moisture very often is the limiting 
factor in growth and crop production. The moisture problem perhaps is the 
most serious one which fruit growers have to face. 

Root anchorage and feeding space (considered as one factor) give rela- 
tively less trouble than either a correct water supply or a proper supply 
of plant food. The latter factors must receive attention in all soils; the 
former only in certain soils of a hard or uninviting nature, or which 
are in bad condition owing to improper treatment. A light, porous, 
fertile soil offers no difficulties to roots in their penetration and food 

gathering, but a hardpan soil, a 
heavy clay or a cemented gravel 
soil does offer serious difficulties. 
All orchardists agree that an 
extension of the root anchorage 
and feeding scope of trees is bene- 
ficial and desirable. Authorities 
continually remind us that we 
should drive the roots down away 
from the surface. One of the 
tests of the 
Root Anchorage thrift of a 
and Spread tree is to 

examine its 
roots for the size and nature of 
their growth. If they are long, 
ropelike and few, the tree is 
starving. If they show as a mass 
of fibers growing from well pro- 
portioned main branches, which 
extend to a fair distance in every 
direction, the soil is full of the 
needed foods and moisture. Only 
trees which are firmly and deeply 
rooted will stand up against wind- 
storms and under loads of fruit. 
It is largely to bring about the 
conditions outlined that orchard 
ground is cultivated. 




These two trees were washed out of the ground 
with a stream of water from a hose, in the fall of 
their first season after planting. The one on the left 
had been set in an ordinary hole, dug as usual. The 
one on the right had been set in blasted ground. The 
soil is typical redshale (Upshur), classed as clay loam. 
(New Jersey Experiment Station, New Brunswick, 
N. J.) 



What Soil Is 

The material we call soil may be described as the outer layer of the earth. 
The soil includes loam, clay, sand, gravel, boulders and even ledges of rock. 
To limit the soil to the earth penetrated by roots would leave out other material 
underneath of exactly the same stuff. To limit it to what we call loose earth, 

105 



leaving out rock, shale and the like, would not be correct, since the rock and the 
soil are composed of the same elements. Often the point where "soil" begins 
and "rock" ceases is indistinct, as in the case of hardpan, for instance. 

The loose earth, or ground, is only particles of rock that have been more 
or less changed by and mixed with the remains of plants. There was a time 
when there was no loose soil. The surface was rock. As 
Origin of Soil the seasons passed, water dissolved and wore away particles 
of the rock. After a time mosses and rock plants appeared 
and sent their roots into crevices. The roots grew and helped to split off other 
fragments, and when the plants died their material gave off acids which helped 
the water to dissolve more rock and to dissolve it faster. 

Frost and heat from the sun hastened the processes till the softer minerals 
separated from the harder ones, and what was not washed away by running 
water caved in and became mixed with dead moss and the decaying roots and 
stalks of grass and other plants. 

This is soil at the present time, whether it is hard or soft. 

The top-soil of cultivated land ordinarily shows a much more advanced 
stage of this breaking down process than the subsoil. The top-soil, which 
usually is the layer reaching to the furrow depth, 
Top-soil and Subsoil generally is darker colored, from the greater amount 
of remains of plants it contains. It differs from 
subsoil in porosity, moisture content, bacterial activity and in other ways 
which will be explained fully farther along in this bulletin. 

Whatever the difference, it is largely a difference in the stages of decompo- 
sition or disintegration of the mineral particles, and of the amounts of organic 
matter present. Both surface and lower soils are essentially of the same chemi- 
cal make-up and they both may have come from identically the same kind of 
rock. The ground near the surface has been exposed to action of heat and 
cold and water and air and plants, and has been changed more than the ground 
under the surface. The more the soil is broken down from the original rock 
the finer the particles are, and in general, the more fertile it is. 

It is well at this point to call attention to the latent strength in the soil, 
to counteract any tendency toward the belief that you must put back in as 
much as you take out. The soil is not a sort of empty mill into which you 
pour plant food and take out crops. It is to a large 
The "Strength" in Soil degree an inexhaustible mine of many plant foods. 
As evidence, look at the immense growth that has 
arisen from it in moss, weeds and forests during the thousands of years past. 
If all this growth were piled up it likely would weigh as much as the soil itself 
to a great depth. In the soil and air now, waiting to be released and used, is 
substance enough to create food for all the people of the earth for years without 
end. In the soil of your own orchard and farm you likely have nearly all the 
plant food elements your crops ever will need. Make them available for roots, 
add to the supply the few that are short, and in crops you can profit from 
nature's riches as surely as though you were digging gold or coal. 



106 



Tillage Produces 
Fertility 



The Relation of Tillage Blasting to Soil 

That "tillage is manure" is no new thought. The phrase itself originated 
a great many years ago. The proof of its truth lies in the very nature of soil 
itself, which has been explained in the preceding chapter. Tillage, which is 
the stirring and mixing of soil, promotes and helps these 
natural processes which first changed the rock into soil, 
and which now tend to make the soil fertile. 

A good, deep plowing, followed by thorough harrow- 
ing, opens up the soil so that roots can penetrate it easily. It introduces air. It 
helps to maintain moisture in dry weather. It exposes a new part of the soil 
to frost and to sun. A new supply of the plant food elements which the soil 
contains is liberated, or it is better to say their liberation is hastened, and trees 
are given a better chance to grow. 

The so-called "run-down" or "worn-out" soils contain almost as much of 
most plant food elements as ever. But instead of the soil being soft and 
mellow, it has reverted and become harsh. A run-down soil shows under chem- 
ical analysis a composition not greatly different from what it does before becom- 
ing exhausted or after it is made fertile again. The only vital difference is 
the state or condition of the plant food elements. 

Tillage alone of course will not keep land from running down. Plants also 
are needed for supplying vegetable matter in the soil. Their dead roots and 
stalks hold the particles of the soil in crumbs, increase its moisture holding 
capacity and help to maintain conditions under which further decomposition 
occurs continually. Without tillage the plants will not grow or at least will 
not become mixed with soil farther down than a few inches. 




Cherry trees three years old, with corn intercrop, which certainly takes some plant food. The soil 
naturally is no better than in the other part of the same orchard, shown on opposite page, but it was 
veil broken up with explosives. 



107 



Under wild or forest conditions with no tillage, the fertility of the soil is 
maintained and even increased, but the processes are very slow and the result 
is long in coming. In orchard soil the processes must be hastened so that the 
natural forest changes of 25 years take place in one. 

When an explosion takes place in soil, the gases escape in all directions 
from the place where the dynamite charge was located. Those gases which 
start downward and sideways soon curve upwards. They travel sideways 
several feet through the soil. They lift the soil in mass and make it break and 
crumble, and can be detected rising from the ground over a circle 1 to 15 feet 
in diameter about the position of the charge. 

The gases of an explosive will rebound from a substance that is extremely 
hard or resistant, but they try hard to travel in a straight line in the original 
direction. When confined in hard soil, they strike against the resistance, and 
because the mass of soil is not firm enough to turn them aside, it is broken and 
crumbled. They smash right through compacted sections. This fining and 
crumbling action can be compared to the effect of pounding up a brick with a 
hammer. The tens of thousands of particles that had been clinging together 
in one hard mass are separated. 

It is this fining and loosening which makes so valuable the particular kind 
of tillage which blasting gives. (It is intensive tillage— the kind which is 
"manure.") In modern agricultural practice intensive tillage is recognized as 
one of the best means of securing large crops — in fact, it is recognized as a 
necessity in orchards and in fields and gardens where intensive crops are grown. 
Blasting is tillage of the most intensive kind it is possible to secure by any 
practicable means. 

The limit of plowing, even with deep tillage implements and subsoilers, is 
1 6 to 18 inches. The shallowest blasting should reach to a depth of 36 inches, 



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■•■ • ' .■ .... /'; •i'/j Ir*-. >« ( ■' .,-' i" ... .■ 



In this orchard the trees are seven years old, but much smaller than the other, three-year trees. 
The fine growth of clover proves that top soil is fertile and in good condition, yet it does not grow 
trees as well as the blasted soil. 



IJ8 



and the average work is done so as to reach to 48 inches or deeper. The real 
significance of such deep, intensive tillage is so far beyond the mere superficial 
appearance that it must be explained in separate chapters. 

How Root Growth is Helped by Deep Tillage 

A mature apple tree should have a root system spreading twice as wide 
as its spread of limbs, with some roots at least 10 feet deep, and a large part 
of the root system deeper than 2 feet. With roots less well developed and 
distributed, the tree is bound to suffer from lack of water, and plant food, and 
possibly from wind. 

Fully developed peach trees have root systems smaller in proportion than 
apple trees. Pear, plum, quince, cherry, nut trees, citrus fruits, and the semi- 
tap root shade trees in mellow soil develop root 
Depth and Length to systems not greatly different from apple trees in 
Which Roots Grow extent. Some ornamental trees, such as Norway 
pine and shagbark hickory, often grow half as deep 
into the ground as the trunk is tall. Grape vines have roots extending in every 
direction to a length out of all proportion to the size of the vines above ground. 

These developments occur only when the ground is as loose, fertile and 
well watered as ic should be. In orchards or hardpan soils and neglected soils, 
the roots grow out to a length less than the length of the limbs. They go down 
until they strike a compact layer of clay, a layer of hardpan, or the water table. 
Unless forced and coaxed down by cultivation, they grow up until you can see 
them where they bend above the surface. 




The apple trees in these pictures were planted 19 years ago, in soil with hardpan about a foot 
under the surface. The tree at the right, in the picture, was planted without breaking up the bed with 
explosive; that at the left set in blasted ground. 

Today some of the trees not growing in blasted ground are dead, while all those in blasted ground 
are living. Those in blasted ground average 25 feet high, and in unblasted ground 18 feet. The former 
trees have an average spread of limbs of 25 feet; the latter, 16 feet; while the trunks of the two sets 
of trees measures 3 feet 7 inches and 2 feet 3 inches, respectively. In the blasted ground the trees 
stand "shoulder deep," and over the unbroken hardpan the roots are raised above the surface, as the 
pictures show. 

This is one of the most striking instances of the damaging effects of a hard and impervious soil 
that has ever been examined carefully and photographed. (Geo. W. Brown, Mount Cory, Ohio.) 

109 



The big root systems can be picked out by the appearance of the trunks 
and tops of the trees. No small, scrawny trees have well-developed and widely 
extending roots, nor will any large, thrifty trees have short and meagre roots. 
A tree that regularly grows and ripens a heavy crop of good sized fruit must 
have a big, deep root system. Any tree that does not cannot do the work. It 
follows, in view of these facts, that every orchard and ornamental tree should 
have roots extending as wide and as deep as possible. One or 2 feet deep is 
not enough. With roots only at such depths the trees exhaust the little bit 
of moisture within their reach during 3 or 4 weeks of rainless weather; or worse, 
they may be blown over by the first stiff wind. 

Young trees have even greater need of proportionately big root systems 
than mature trees. Their roots need to go down 3 feet at least by the end of 
the second year after their planting and should extend laterally 6 to 8 feet 
then, even if the trunk is only 4 feet high. All that is said about root growth 
applies equally in the case of the newly planted tree and the tree that has been 
in place many years. 

The Causes of Restricted Root Growth 

The limiting factor as to depth of root growth may be some form of hard- 
pan or cemented gravel, compact clay or other soil, poor drainage, or simply 
that the soil contains neither enough water nor enough available plant food. 
An idea of the difficulty encountered by roots in pene- 
Hard Soils Difficult trating soil can be had by noting the method of their 
to Penetrate growth. A hair-like or pin point of a rootlet presents 

its tip in the direction it is growing. This new tip 
then expands like a bud in the spring, pushing back and lifting the soil or earth 
out of its way. 

When the soil is soft and porous, the roots find little difficulty in penetrat- 
ing it, because its minute air spaces serve as ready-made tunnels; but when the 
soil is compacted or cemented, as it is in hardpan, in hard gravel deposits, and 
in all harsh soils having little organic matter, the delicate, minute roots are 
compelled to do work which almost would defy a steel rod. 

True hardpan is semi-rock. You cannot crumble off the edges of a chunk 
with your fingers. The softer type can be cut with a sharp knife, as clay can 
be cut, but the point of the knife cannot be forced into it without pressure or 
pounding. It is not surprising that such soil resists root penetration. 

A hardpan layer, or one of clay, plowsole or other structure, can be com- 
pared to a plank floor underground. The roots will run along it in the softer 

soil, but they will not penetrate it. When a young 
Hardpan is Like Wood tree is planted in a small hole dug in compact 

soil, it is, practically, in a wooden tub. The roots 
have to force their way through the hard sides in order to develop as the 
roots of a tree should. 

The compact layer of soil may occur within 6 or 8 inches of the surface of 
the soil, or may be down a foot or 2 feet or more. Where within 2 feet of the 
surface, it often forces the roots to lift the crown of the tree entirely above 
the surface. If the entire root anchorage and feeding space of a tree is con- 
fined to the first foot or two of soil, it cannot grow or yield to anything like 
its maximum capacity. 

To help to make clear the great difference in the case of root penetration 

110 



through hardpan, stiff clay or other tight soil, as against field soils in mellow 
condition, a statement of the amount of air space in soils 
Porosity of Soils may be of value. When a hardpan, clay or gravel soil 
has been thoroughly compacted by water or other agency 
so that the particles are packed as close as possible, the air space (or pore 
space or porosity) is only 5% to 10%. 

The soil is 90% to 95% solid. This is the hardpan, cemented gravel and 
plowsole condition. But the average air space in soils in good condition is 6 
to 13 times as much, as the following table shows: 

Approximate Amount of Air Space or Pore Space in Soils in Good Tilth 

Clean sand 33 Per Cent. 

Coarse sand 40 

Medium sand 41 

Fine sand 44 

Sandy loam 51 

Fine sandy loam 50 

Silt loam 53 

Clay loam 54 

Clay 56 " " 

The nature or character of the root growth is modified by the comparative 
mellowness of the soil. The ideal feeding roots, it is everywhere agreed, are 
fine, fibrous and not long. The main or anchorage roots should extend well 




The nature of root growth of fruit trees depends on the condition of the soil in which they grow. 
The ground was dug away from the roots of two trees, leaving the main roots in their original 
positions— (See next page) 



111 



out from the tree and down deep, gradually tapering from a thick base to a 
slim point. All along them the tendril-like feeders should grow out like the 
legs of the so-called "thousand-legged" insects. 

In a tight soil the main roots usually grow short and stubby, with few of 
the fine feeding roots. In a very poor soil the main roots lengthen into veri- 
table ropes, traveling on and on in search of food. They are usually almost 
bare of feeders. Under any conditions of soil except that of the best tilth an 
excessive part of the strength of the tree has to go into root building and root 
penetration, rather than into food gathering. Too much time is consumed in 
growing the root. Five years may fail to develop a root system equal in food 
gathering capacity to a system developed in one year in soil of proper texture. 
The limited digging usually done in making holes for planting trees serves to 
give the roots a brief start. The hole should be dug at least 3 feet deep and 
4 feet square, but few indeed are the instances of the digging of such large 
holes in commercial orchard planting. The usual prac- 
tice is to scoop out just enough ground to let in the severely 
trimmed roots to the required depth. 

Quite often young orchard and shade trees are set in 
holes not more than a foot deep and 18 inches wide. The sides of the holes 
frequently curl the ends of the roots back like clinched nails. An examination 
of trees that have been dug up or washed out a couple of years after they had 
been planted in dug holes, shows that masses of matted and twisted roots have 
been confined in the hole that was dug, almost like the roots of a large plant in 
a small flower pot. 

How to Secure Big Root Development 

The way to do this is to break up the soil with tillage, and to make it fine 
and porous. Tillage with plows and cultivators can be extended to a depth 



Tree Holes Dug 
by Hand 



r 



s 




—Note how the hard ground under the one tree kept practically all its roots in the top two feet of 
soil. The soil under the other tree was lighter and more porous, but not fertile, consequently 
the roots grew like long ropes, traveling many feet in all directions. Both are poor root systems. 



112 



Deep Tillage Insures 
Big Root Systems 



of 8 inches without trouble. By using subsoil attachments and deep tillage 
disk implements 18-inch tillage is practicable. 
Where it is desired to go deeper, hand digging and 
blasting are the only means available. Hand dig- 
ging of all the soil is impracticable in commercial 
orchards, but if the cost does not matter, the ground of home fruit gardens and 
lawns can be worked over by hand to a depth of 4 to 5 feet by digging wide 
trenches and shoveling the ground back from each new trench into the old one. 
This is a common practice in many European gardens. 

Tillage by blasting is pre-eminently the most advantageous treatment for 
the soil that is hard enough to restrict root growth or to hold free water. In a 
previous chapter the action of a proper blast has been described. It is clear 
that the explosion, in breaking up the hardpan or the plowsole or the layer of 
stiff clay or cemented gravel; in opening cracks through the soil in every direc- 
tion, and in crumbling and fining the earth to a depth of 4 or 5 feet or more, as you 
place the charge, supplies just the treatment needed. By no other practicable 
means can the soil be worked to an equal depth, and in no other way can 
even the top 2 or 3 feet of soil be worked so thoroughly at a reasonable cost. 

After considering the foregoing facts the thinking man will need no con- 
crete examples of better root expansion in well tilled soil to convince him that 
roots will develop when given the chance and the incentive. 
The illustration on page 1 05 shows this so well that every 
reader should look at it now. Two young trees were 
washed out of their beds. Both had grown one season. 
The root system of the one in blasted ground is about 4 times the size of the 
other, and it is of a better character. 



Roots in Blasted 
Ground 



. **i -i 










'B^jffi^a: 




In the orchard where these two trees are growing are many thousand set in blasted ground and a few hundred 
in unblasted soil. Not as many died as a result of planting each 1000 in the deeply loosened ground as of each 
100 in the unbroken soil. The growth made by each class of trees up to the end of the second year after planting 
is shown in the pictures, which are of typical trees from each lot. (The Belmont Orchard Company, Charlotteville, Va.) 

113 



This example is not advanced as typical of all results. The growth that 
will be made by any tree cannot be predicted. Too many other factors aside 
from the condition of the soil enter into the matter. The fact that some trees 
in properly blasted ground have grown as much in 
Amount of Increased 2 years as others in unblasted ground have grown 
Growth in 4 years is no guarantee that all trees will do as 

well, or may not do better. If the blasting is not 
done right no benefit at all may be derived; indeed, there are cases on record 
where positive damage has been done to soil and to trees by improper blasting. 

There are but few soils in which intensive tillage of any sort will not help 

the root growth of trees. Among them may be 

Soils That Should Not mentioned loose, light sand, gravels and loams 

be Tilled Deeply which are as porous and mellow as they should be 

without further loosening. The volcanic ash soils 
of some Rocky Mountain states need no deep tillage unless underlaid with 
more or less crusted lava. 

Whether or not to blast loam soils to secure better root penetration depends 
on their character and condition. If they are deep, well drained and well 
supplied with humus, the chances are that little increase in root growth will 
be derived from any sort of deep tillage. But considerations in respect to mois- 
ture storage and the liberation of insoluble plant food nearly always call for 
tillage and yet more tillage. Roots of cover crops must penetrate the ground 
in order to keep soil fertile. Hence few soils aside from those named above 
will not be benefited by deep tillage. 

Correct methods of doing the blasting to put soil into proper condition 
for root development and for other purposes are described on pages 131 to 1 38. 
On page 140 you will find a discussion of the length of time one thorough 
breaking up of the soil may be expected to last, and of how the needs of trees 
may be met both at the time of planting and years later, when the roots have 
extended themselves many feet in all directions. 

How Soil Water is Governed by Deep Tillage 

In every orchard soil the water problem is two-fold. Surplus water must 
be drained away and sufficient moisture for use of the trees during dry weather 
must be stored. Both purposes are served by tillage in ways that are made 
plain in the following explanations. 

The drainage must be effective enough to take away the excess water 

quickly, but the flow of water must not be so fast as to leach or float away 

much plant food. Whenever the excess water is permitted to run over or 

through the soil in trickles, it leaches out available plant food. It 

Leaching should filter away — without delay or damming back, but still 

filter — through beds of fine, granular soil. 

The water should escape at a lower level into a ditch or into a loose layer 
of gravel or sand that will carry it away. In orchards the level of standing 
water in the soil must be well below the depth of root penetration if the 
trees are to grow and yield well. 

Conditions Necessary for Drainage 

To a great extent the drainage problem is to put the soil in condition by 
tillage to act as a filter bed. The soil must be kept loose enough to let the 
water seep and percolate through. Layers of tight soil, such as compact clay 

114 



or hardpan, hold the water as though it were in a tank 
Proper Drainage or a pan. It cannot escape except by evaporation. 
Such tight soil must be broken up to a depth that will 
permit the lowering of the water-table below proper depth for root growth. 

If the layer is thin— say only a couple of feet through— all of it can be 
reduced to fine particles. When it is thicker than 4 or 5 feet it cannot be broken 
entirely through to softer ground below except at prohibitive cost, and the 
effort should be to create a zone of proper condition in the top 4 or 5 feet of 
the ground. From this the water should drain away into ditches. 

Even in soil containing no clearly defined hardpan, the general texture 
and condition may be such as to make drainage poor. Tillage will remedy 
this condition, by opening up and fining the soil so that water can move about 
in it freely. 

The statement of the porosity or air space of soils in the chapter on root 
penetration (page 1 1 2) will be interesting in this connection. In a hardpan or 
thoroughly compacted clay there is an average pore space of only 5% to 10%, 
but when the same soils have been reduced by thorough tillage to a proper 
condition of tilth they contain upwards of 40% on the average, or 6 to 13 times 
as much pore space. In other words, nearly half of the bulk of the soil is air 
space, open to the free movement of water. Naturally such well-tilled soils 
are well drained. 

Moisture Storage 

The amount of water that in a dry season must be stored somewhere in 
the soil, available for the trees, can be stated with a fair degree of accuracy 





A direct comparison in growth. The superior soil conditions brought about by intensive deep tillage are 
responsible for the gain of the one tree over the other. Such marked results are not always produced by blasting, 
however— only when the soil is of a nature and in a condition to respond quickly and heavily to the action of air, 
moisture and bacteria. (Auburn, Ala.) 

115 



in terms of inches in depth. It must be based, of course, on the needs of the 

crop of twig growth, leaves and fruit. For each ton of 
Amount of Water material grown (dry) it is safe to say that at least 3 
Used by Plants inches of water will be used by the trees. If the orchard 

crop weighs 5 tons to the acre, which probably is less 
than the average, the amount of water required is 1 5 inches in depth over the 
acre. This amount meets only the actual needs of the trees, and does not allow 
for much waste through surface evaporation. 

Fifteen inches of water is the net amount that will be required to make the 
growth and yield of the trees. Less water available for the roots will mean 
decreased growth and fruit production. If irrigation is not practiced, the one 
safe procedure is to store the required amount of water in the ground, for rain- 
fall is uncertain, and cannot be depended on. 

The capacity of a well-drained soil to hold water in a 
Amount of Water condition in which it is useful to trees depends on its 
Stored by Soils structure and condition. Laboratory tests of average 

field soil in excellent tilth have shown in the first 4 feet 
down from the surface the amounts of water given in the table below. 

Amount of Water Contained and Useful in Different Soils When Tilth is Good — 

Top 4 Feet Fully Loaded 

Amount water Water Inches 

(inches deep) weight Unavailable available 

Coarse sand 7 11% 3% 5 

Light silt loam 14 21 10 7 

Fine sandy loam 11 18 5 8}/^ 

Clay 16 30 17 iy 2 





The superb soil conditions produced by intensive deep tillage are nowhere of more value than in orchards 
of citrus trees. These two trees, both Valencia orange, both 15 years old, were planted side by side. The one in 
unbroken soil is only 8 feet high. The other is nearly three times as high and -"ore than twice as broad. (E. C. 
Franzen, Santa Ana, Cal.) 

116 



Not All Soil Water 
Can Be Used 



These soil types are named for purposes of illustration. The moisture 
content of other soils can be judged from these figures. 

The figures in the first column indicate that clay and light silt loam to a 
depth of 4 feet might contain enough water for average crops of fruit, while 
in coarse sand and fine sandy loam trees would run short. But only part of 
the water can be used. In clay soil, for instance, trees will wilt when the ground 
still contains about 1 7 per cent, of water. This leaves 
only 7j/2 inches in depth of water out of the total 
supply of 16 inches when the soil is filled to capacity, 
that the trees actually can use. The proportion of 
water that can be used in the other soils is shown likewise in the table. 

It follows that all the water that can be stored in the top 4 feet of any 
soil is not enough for a fair crop of fruit. The supply must be increased. The 
trees must get a part of their supply from the subsoil beneath the 4 foot level. 
This brings us to a consideration of the manner in which water is stored in the 
soil and the ways in which it moves about. In previous reference to the pore 
space or air space in soil (page 1 1 4), the free drainage of excess water was men- 
tioned. Water which will percolate and seep down through 
the pores of the soil owing to the action of gravity is harm- 
ful to all fruit and ordinary shade trees. The roots cannot 
or will not take it up in this form, and are damaged by it. 
The only form in which roots take up water is when it clings to particles 
of soil as films. This is called capillary water, because it is held to the par- 
ticles by capillary force. What this force is and the form in which the water 
is held can be illustrated better than described. Put your finger in water and 



How Water is 
Stored in Soil 




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ifc^il^"" -**' : 


'**. *fci^ J 


Xd» ■ .--%k '-** 




1I&SB& 


''*•* ■ 



A tree should show greater proportionate superiority owing to intensive deep tillage in its second year than its 
first after planting. This is on account of the roots penetrating deeper and wider in the broken soil, and the increased 
plant food released and made available. Tillage merely starts the beneficial soil processes. Time is needed before 
the results show. The two trees shown here demonstrate this truth. Both are at the end of their second year's 
growth in their present beds. One bed was blasted ; the other not. (Fred W. Miller, Millersburg, Penna.) 

117 



it comes out wet. Put it in quicksilver, and it will come out dry. Some of 
the water is held to the skin by capillarity, but none of the quicksilver is so held. 

After excess water has drained away from the soil particles, they are wrapped 
in films of water which can be more correctly called moisture. This moisture 
is held to them by capillarity until it is taken away by evaporation or by roots. 

If one particle should happen to have less moisture than its neighbors, 
capillary force causes some of the bigger supply to creep from surface to sur- 
face till the amount is equalized throughout the soil. The movement of capil- 
lary moisture is not limited to the one direction — downward — as free water is 
limited. In this form moisture moves upward and sideways as well. The 
movement can be illustrated by the movement of oil in a lampwick, or of ink 
in a blotter. 

Now the movement of capillary water toward the surface from a depth 
greater than 4 feet is free and abundant when soil conditions are right and 
there is an abundant supply below. It, however, depends on the fineness and 
arrangement of particles and the pore space of the soil. The soil must be fine; 
the particles must touch one another; but they must not be so packed or jammed 
together that the pore spaces are squeezed shut. If the particles are round, 
they should touch one another only at minute points on their surface, as 
apples touch when properly packed in a box. The logical way of feeding 
moisture to trees or plants is to send the roots down after it. Capillary move- 
ment, however, brings the moisture to the roots as they use up the supply 
they are in contact with. 

The reason behind the necessity for a comparatively loose condition of 
soil is easy to see when we remember the films in which moisture is held. Reduce 
the surface space of the particles and we reduce the surface area which can 
carry moisture films. 

The size of the particles governs directly the extent of the surface area 
in a given bulk of soil, and consequently the amount of film moisture it holds. 
As it is illustrated often, a solid rock in the form of a 
Film or Capillary cube, measuring 3 feet high, 3 feet wide and 3 feet thick, 
Moisture Supply has 54 square feet of surface area. Reducing such a 
rock to pieces measuring an inch on a side increases the 
surface exposed to nearly 2000 square feet. Reducing the pieces to the size 
of soil particles increases the area in proportion. 

As applied directly to the soil, the facts regarding the number of particles 
and their surface area are striking and wonderful. The table below gives the 
figures. 

Number of Particles and Area of Their Surfaces in Different 
Soils in Good Tilth 

Sq. ft. Sq. ft. 

Number particles surface area surface area 

Soil per pound of soil per pound of soil per cu. ft. of soil 

Coarse sand 1 ,326,600,000,000 405 40,500 

Medium sand .... 1 ,724,700,000,000 473 44,500 

Sandy loam 2,91 4,000,000,000 8 1 6 66,600 

Silt loam 4,287,000,000,000 1 340 1 04,000 

Clay loam 6,81 1 ,400,000,000 1 825 1 36,500 

Clay 8,231,100,000,000 2000 142,000 

The significance of the figures in the last column will be plainer when it 
is recollected that an acre contains about 43,000 square feet. Each cubic foot 
of medium sand contains about an acre of surface of particles on which moisture 

118 



film can be held, and each cubic foot of clay contains upwards of 3^2 acres of 
such surface. Therefore an acre of soil to a depth of a foot may contain up- 
ward of 43,000 to 1 40,000 acres of moisture film when in proper condition. 

The figures are illuminating in respect to the varying moisture-holding 
capacities of different soils. Sand has less than one-third of the capacity of clay. 
These differences should be kept in mind. 



The Moisture Supply Depends on Depth and Thoroughness of Tilth 

The figures for the amount of water soil can hold are based on soil in first- 
class condition of tilth, with normal porosity of 30% to 50% and with the 
usual amount of organic matter. Soil that is compacted, 
Good Tilth cemented, run together or lacking in humus will not have any- 
thing like the stated amounts. Also the movement of water — 
the drainage of free water and the movement of capillary water in dry weather — 
will be restricted very greatly. 

Emphasis must be placed on this matter of organic material in the soil. 
It constitutes one of the most important elements that go to make good tilth. 
If organic matter is lacking the soil will run together and within 2 or 3 years 
will become harsh and unpleasant in spite of the most intensive tillage. 

The way to insure the necessary 15 inches or more of 
net depth of water needed to grow full-sized crops is to fine 
and loosen the soil thoroughly to a depth of 4 feet or more 
in order to store the maximum of moisture, and then have 
the ground below this depth in such condition that capillary moisture will rise 
without restrictions. 

Tillage must be thorough and deep to promote drainage and to put the 



Organic Matter 
and Moisture 





One tree new from spring to fall in blasted ground; the other alongside it in unblasted ground. The trees both 
are Yellow Transparent, 2-year when set out, and of equal size then. (E. G. Sexton, Canton, Ga.) 

119 



soil into condition to store sufficient moisture. If it is not the soil below the 

furrow depth becomes compacted and hard. 
Deep Tillage Demanded The particles of soil run together till their water- 
holding capacity is only a faction of what it 
ought to be and can be under normal conditions of tilth. 

Something can be done toward increasing the moisture storage capacity of 
soil by breaking to a depth of 1 6 or 18 inches with subsoil plows and deep til- 
ts K "1 T>1 " ^ a § e implements' But the execution done by proper 
g bl as tj[ n g i s better in proportion to its increase in depth. 

Thoughtful orchardists will see that there is no practicable way of getting 

the soil worked and loosened at sufficient depths other than by blasting it. 

Blasting will do it — and in connection with regular and cover 

Blasting Soil crops to keep up the organic matter will insure each season a 

supply of moisture sufficient for heavy crops in dry weather. 

In case layers of hardpan or clay interfere with the movement of water, 
they should be broken up. Soil should be examined thoroughly for any such 
conditions. 

The conservation of a moisture supply by shallow surface tillage is a gen- 
eral practice. It need not be described here other than to say that a 2 or 3 

inch layer of loose, dry soil or dust will isolate 
Surface Mulch Required the moist soil beneath and prevent the escape 

into the air of the water it carries. Deep tillage 
will help to provide the storage of a supply of water, but it will not conserve it. 
This moisture conserving (mulching) tillage on the surface is absolutely necessary. 

But no amount of surface tillage will conserve moisture that is not stored 
in the soil. Enough rain falls during the growing weeks of some seasons to 
supply the needs of heavy crops, but every orchard in which the soil is not 
deeply tilled is bound to suffer from drouth frequently. The outstanding 
fact is that deep tillage is required before an adequate supply of moisture can 
be assured every summer. 

How Deep Tillage Increases Fertility 

The proper proportion for the different plant foods previously mentioned 
in the soil cannot be stated exactly, because different plants and trees require 
different amounts. A slight excess of any element will do no harm. 

The so-called chain theory of plant food needs has been proved true so 

often and so extensively that it is to be considered 

Balancing Plant Foods no longer as a theory, but a fact. Briefly, this 

rule is to the effect that the thrift or growth of a 
tree or plant is governed by the amount of that plant food in which the soil is 
weakest, proper balancing considered. 

If a certain soil contains — we will select arbitrary figures for the sake of 
illustration — in each cubic foot 6 units of nitrogen, 1 units of phosphorus and 
20 of potash, while the need of the crop grown in this soil is 10 units of nitrogen, 
20 of phosphorus and 12 of potash, the crop will not be a full one. It likely 
will be three-fifths of normal size, because growth will be held down by the 
lack of enough phosphorus and nitrogen. The oversupply of potash in the 
soil is of no use because one plant food cannot be used to any practicable 
extent in place of another. 

This one illustration is enough to make clear the idea of the necessity for 
having all plant foods present and available in abundance. There is nothing 

120 



mysterious in the fact of a crop failure, nor need there be much doubt about 
what constitutes proper fertilizing of land. 

But knowing what elements of food are needed is only half the battle. It 
is equally important to know where to get the necessary material and how to make 

it available for roots, certainly, cheaply and quickly. 
Plant Foods of the Soil As stated on page 1 06, the usual orchard soil con- 
tains an abundant supply of available plant foods, 
excepting only of nitrogen, phosphorus, potash or lime, which may or may not 
be present in sufficient amounts. 

The nitrogen can be secured in unlimited quantities from the air and put 
in the soil by proper use of legumes. 

The lime must be added in the usual way. 

The Phosphorus and Potash Problem 

A chemical examination of your soil, to a depth of 1 to 6 feet or more, 
if it is clay, loam or sand, likely will show figures for the amount of potash 
and phosphorus present that may surprise you. To make them apply more 
easily to the usual field condition, the following data are based on an acre, 
but of course do not apply accurately to all soils. 

The amount of potash in the soil of "new ground" to a depth of 7 inches, 
the usual furrow depth, will run as high as 60,000 
pounds. It may be as low as 20,000, but it will 
average up to 40,000 to the acre. The soil to a 
depth of a foot, therefore, contains more than 
100,000 pounds, or 50 tons of actual potash. To a depth of 4 feet the 
amount is 200 tons to each acre. 



Amount of Phosphorus 
and Potash 





The growth of shade and ornamental trees is governed by exactly the same principles as that of orchard trees. 
They must have enough moisture, nitrogen, potash and phosphorus, and must have root anchorage and feeding 
space. In a yard or lawn the soil conditions are such usually as to be benefited particularly by the intensive deep 
tillage given by blasting, as these two pictures demonstrate. (St. James, Mo.) 

121 



The amount of phosphorus is smaller, but still is formidable. It runs as 
high as 25,000 pounds to the acre in 7 inches deep of soil in some of the better 
new lands, falling to only a few hundred pounds in poor lands. In all new 
lands in good tilth it will average around 8,000 pounds to the acre in the clay, 
and about 2,500 pounds in loam. In soils that are run down the phosphorus 
usually is used up till less than 1,000 pounds and sometimes only 200 pounds 
to the acre remains in the top 7 inches. 

Taking the above average figures, each foot deep of fertile loam contains 
upward of 2 tons of actual phosphorus and each foot of clay, 8 tons. Four 
feet of soil over an acre contains 8 tons and 32 tons respectively. 

The different fruits and other crops require varying amounts of plant 
foods, as mentioned at the beginning of this chapter, but a sufficiently clear 

idea of their average requirements can be secured 
Amount of Plant Food by examining the demands of a wheat crop. 
Used by Trees Wheat requirements are not essentially different 

from those of apple, peach and pear trees. 

Trees use the most of their potash and phosphorus in growing leaves, twigs 
and bark, and little in growing the fruit. The food elements in the leaves of 
trees, of course, are returned to the soil each autumn, but those used in making 
wood are permanently removed from the soil. 

Erosion and leaching take away some plant food. This loss, of course, 
must be added to the amount carried away in crops. Tests have shown the 
loss to be about one-eighth of the amount consumed by average crops. Nearly 
all of this comes from the few 
top inches of soil. The top inch 
or two of some soils is leached 
"dead." 

The store of phosphorus in 
the soil, we have seen, is much 
less than that of potash — averag- 
ing one-half to one-fifteenth as 
much — but the amount consumed 
and carried away by crops is 
nearly equal. Therefore, the 
phosphorus supply is subjected 
to a much greater drain in pro- 
portion, and will be exhausted in 
much less time. In many soils it 
is already seriously depleted, if 
not practically exhausted. 

In the chapter which de- 
scribed the formation and nature 
of soil, it was pointed out that 
heat, cold, water, air, bacteria 
and other natural agencies had 

manu- 

f a c - 

tured 

the 

called 




Natural Plant Foods 
Insoluble 

loose earth commonly 
"soil" by disintegrating and 



It is extremely important that an evergreen tree 
should have its roots below frost-line, on account of 
the evaporation of water from its needles during the 
dormant period. Cut off evergreen roots from mois- 
ture and they quickly dry out. The resin in their sap 
hardens. When this happens the tree is doomed, 
because the sap never again will soften and flow. 

122 



Liberations of Natural 
Plant Foods 



decomposing rock. That is, they broke it down from solid rock to the softer 
stage, of more or less fine particles. 

Now, plants require their food to be dissolved in water before the roots 
can take it up. They take their potash and phosphorus and nitrogen and other 
foods as soup instead of solids. But these food elements will not dissolve in 
water as they exist in the soil. They first must go through certain chemical 
changes. 

The agencies which produce the changes are the same ones which brought 
along the processes of decomposition of the original rock so far — water, air, 
bacteria and the others that have been named. To these may be added organic 
matter and lime. In the ordinary course of events in an unworked soil, such as 
in a forest or a field only plowed, the subsoil is but little disturbed and none 
of these agencies is permitted to do much work. An occasional root pene- 
trates deeply, a mole or a squirrel or other animal may dig a tunnel, producing 
the conditions necessary for the liberation of the insoluble food. But in the 
main the freeing of the locked-up elements takes place at a very, very slow rate. 

The problem of the orchardist is to hasten the processes of liberation 
so that the natural chemical changes of dozens of years will take place 
in one season. To accomplish this he has only to expose the particles of the 
soil to the action of his helpers, the water, air, lime, organic matter and bac- 
teria. Moisture liberates plant food directly by dissolving such of it as will 
yield, but whenever there is excessive free water some of the food that is liber- 
ated is carried away with the surplus water that drains out of the soil and some 

more of it is changed back to unavailable forms. 
The most rapid liberation of insoluble foods takes 
place when the water in the soil is limited to the 
moisture held by capillarity. This water wastes 
none of the material it frees. Each soil particle contains some of the plant 

food and its film moisture extracts this and holds 
it until the roots get it by taking up the moisture. 

Air produces oxidation of the insoluble ele- 
ments (as rust) in connection with a proper supply 
of moisture. Organic matter contains acids, which, 
released in the decomposing of the roots and leaves, 
act chemically on the locked-up food in the parti- 
cles and free some of it. Lime acts to some extent 
in a similar way. But by far the greatest amount 
of liberation of the insoluble elements is due to the 
action of certain beneficial bacteria. 

These beneficial forms of animal life cannot 
exist in soil that contains little air, or which has 
either too much or too little water, or little vege- 
table matter. Nor can they exist when the soil 
lacks lime. As soon as the soil is made normally 
porous, as described on page 1 14, the excess water 
drained away and a proper supply of moisture held 
as films about the particles, and when vegetable 
matter in the form of roots and stalks of plants is 
introduced, the bacteria begin to multiply and 
become very active. Under favorable conditions 
they are able to liberate more insoluble potash 

123 




This picture is included to 
show what may be considered as 
standard good growth. The tree, a 
Stayman apple, was planted in 
Maryland, near the Pennsylvania 
line, late in April. The photo- 
graph was made in September. 
The average growth of branches is 
18 inches. (Garacove Farm, 
Northeast, Md.) 



and phosphorus in I or 2 years than has taken place in 100 years without 
them. 

On the majority of farms some potash and phosphorus has been added to 
the top-soil in commercial fertilizers and manures, but the quantity is small 
compared to the original natural supply. 

Recapitulating, the liberating of the insoluble potash and phosphorus that 
is in the deeper soil calls for the introduction of air and the presence of capillary 
moisture and plenty of organic matter. The only way in which the moisture 
can be stored and maintained in dry weather, is by fining and loosening the 
soil, which automatically brings the necessary porosity and air supply and con- 
ditions for root penetration. 





The presence of a large weed and grass growth proves that the soil is fertile. It is not 
detrimental, but helpful, in the orchard after July. Under a system of shallow surface tillage during 
the spring months and intensive deep tillage every few years the food supply will be kept up largely 
by nature. 



The difficulty in an unworked soil is to keep plant foods, particularly 
potash and nitrogen, in an available condition. When bacteria are not active, 
the available fertility reverts to its original insoluble state very quickly. 

Once the soil is loosened, cover crops should be planted immediately so 
that the ground will be filled with roots to a depth of 4 or 5 feet. This is the 
only way raw vegetable matter can be distributed below plow depth. Tillage 
itself will not make the soil granular and mellow. That is a 
Cover Crops result which comes about after proper conditions are estab- 
lished. The proper plants to select for this purpose are those 
which have abundant roots. If the regular crops meet these specifications 
they will do. 

Weeds make good cover crops. Some of the more common weeds, such 
as wild carrot, ragweed, smartweed, mullen and others have the power to take 
from soil — even sandy soil — larger quantities of potash than cultivated grasses 
or crop plants do. They break down insoluble plant foods and store a heavy 
percentage in roots, stalks and leaves. On their return to the soil these stalks 
and roots serve the double purpose of organic matter and of carriers of avail- 

124 



able food. Throughout preceding pages no attention has been given to this 
power of plants to act as miners and refiners of insoluble native food elements 
in the soil. Their action in liberating locked-up elements is considerable. 

To discuss the methods of loosening and fining the soil would be only to 
repeat what has been said in previous chapters. It can be done with a certain 
degree of effectiveness with deep tillage implements 
Methods of Tillage and subsoil plows, but it can be done better by blast- 
ing. The explosives reach down where the tools can- 
not reach — with a thoroughness beyond comparison. 

The vital point is to get the subsoil at depths below a foot worked thor- 
oughly. To depend on the soil above this is to send a boy to do a man's 
work. The use of 3 or 4 feet of soil by the roots, rather than 7 inches, or 
one foot, obviously is bound to be of great advantage unless the top 
Soil foot is exceptionally rich. The rate of liberation of the insoluble elements 
from one foot of soil seldom is great enough to provide food for the 
full crop. From 3 or 4 feet the amount liberated at the same rate will be 3 
or 4 times as great, and is more likely to satisfy the trees. 

Lime improperly applied will cause the soil particles it comes in contact 
with to give up all their plant food, and it will decompose organic matter very 
fast; hence its use should be planned carefully. Burned lime, either steam 
slaked or air slaked, is much more violent in its action on the soil particles 
than ground limestone. The latter is mild and slow when applied in any 
quantity; the former should be strictly limited in quantity and should be 
thoroughly and evenly distributed and mixed with the soil. 

In soil that is properly porous and fine, lime applied to the surface is car- 
ried all through the ground to a 
depth of 3 or 4 feet within a corn- 




short 



com- 



time. In 
when the ground 



This peach tree is a product of intensive deep 
tillage. It was planted in its present bed one year 
and six months before the picture was taken, conse- 
quently it made the growth you see in two seasons. 
(R. C. Walton, Fruit City, Mo.) 

125 



paratively 
pacted soil, as 

under the usual furrow depth has 
not been broken up for years, lime 
organic matter and rainfall — and 
roots — are kept near the surface 
while ground moisture and seven- 
eighths of the plant food that ought 
to be used are kept below, safely 
and uselessly — stored for the bene- 
fit of future generations of farmers. 

The Nitrogen Problem 

The relation of deep tillage to 
the supply of nitrogen in the soil 
is not so direct as to the supply of 
phosphorus and potash, but none 
the less definite. Tillage, together 
with proper accompanying orchard 
practices, will keep the soil sup- 
plied with all the nitrogen the trees 
need. 

In Chile are deposits of nitro- 
gen-bearing mineral, which, in the 
form of nitrate of soda, is used in 



fertilizers to carry nitrogen into the soil. Other commercial fertilizers bearing 

nitrogen are cotton seed meal, bone, meat scrap 
Nitrogen in Commercial and dried blood. In them the nitrogen costs 12 
Fertilizers to 40 cents a pound at usual market prices. This 

nitrogen is an exceedingly expensive plant food 
compared with phosphorus, and compared with the value of the growth it 
makes, though its use in these high-priced forms may be profitable when well 
directed. 

A cheap source of nitrogen, however, is the air. The air is 75% nitrogen. 
Over each acre of ground there is an unlimited supply of it. The cost of getting 
nitrogen from the air is small. In many cases enough 
Nitrogen in the Air other benefits are derived from the process to give a 
profit in addition to the nitrogen. Probably it is 
better to say that the processes which produce the nitrogen are required any- 
how in nearly the same form to establish and maintain good soil structure and 
texture. 

This atmospheric nitrogen gets into the soil as one of the components of 
organic matter — in leaves, stalks, roots and seeds. The plants which are 
richest in nitrogen are the legumes — clovers, peas, beans and vetch. But all 
plants contain some of the valuable substance. 

The amount of nitrogen needed by orchards will likely be 50 to 1 50 pounds 
a season. Heavy crops of corn require 150 pounds. Light crops of wheat 
require as low as 48 pounds. The cost of these quanti- 
Amount Used by ties of nitrogen if all is bought at current prices in corn- 
Orchards mercial fertilizers is prohibitive. 

In the usual soil there is but little nitrogen. A 
chemical analysis likely will show a few hundred pounds to the foot in depth 
over each acre, though soils unusually rich in organic matter may contain several 

thousand pounds. But unlike insoluble potash 
Soil Supply Dissipated and phosphorus, on the ordinary farm nitrogen 

soon becomes soluble in the top foot of soil. When 
the leaves, stalks and roots carrying it decay, it is liberated, and in the free 
state any surplus not taken up by roots leaches away and is lost within a few 
months. On this account the supply in the soil can be kept up only by adding 
to it every year or so the quantity taken out by the trees and lost through inci- 
dental leaching. 

The legumes gather more nitrogen from the air than other plants because 
of certain bacteria which accompany them on their roots, and without which 
they do not thrive. A ton of legume hay contains about 40 pounds of nitrogen. 
The different legumes vary a little in content of nitrogen, and in the amount 
carried above and below the ground. But in general it is near enough correct 
to count that every ton of dry plant growth of clover, 
Amount in Legumes beans, peas or vetch — roots, stalks, leaves and blos- 
soms — will give you the 40 pounds of nitrogen. Since 
an average crop of these plants is a couple of tons or more, their annual use as 
cover crops will increase the supply of nitrogen against all losses without the 
addition of large amounts in commercial fertilizers. 

Legumes get a large part of the nitrogen they use from the air and a smaller 
part from the soil. Before they will succeed, the soil must contain a little 
nitrogen and must be loose and porous. In a soil that is harsh and devoid of 
practically all nitrogen the start should be secured by first using lime and then 
turning under rye, or some other plant that will provide organic matter, thor- 

126 



oughly loosening and fining it at the same time. Conditions then soon will be 
such as to permit of the successful growth of good crops of the more valuable 
plants. 

It is the top-soil that under usual conditions of shallow tillage contains 
practically all the nitrogen. The subsoil contains little or none. The reason 
is that most of the organic matter carrying the nitrogen that is turned under 
is placed in the bottom of the furrow, or is distributed from this depth upward. 
Under any tillage system, the bulk of the organic matter put into the soil 
must be merely plowed down. It cannot be mixed with the deeper soil immedi- 
ately, except in the form of the roots that penetrate deeply and that carry down 
much nitrogen. It is not long before deeply broken 
Getting Nitrogen soil becomes impregnated with a small amount of 
Distributed Deeply nitrogen as far down as it is loosened and powdered. 
This cannot help being of great advantage to trees, 
the roots of which occupy the lower soil rather than the top 7 inches. When 
the trees are compelled to get all their nitrogen out of the top few inches, or 
at most the top foot of soil, in orchards worked no deeper than the plow goes, 
they seldom get all the nitrogen they need because only part of their root system 
can get at it. 

Too much stress cannot be placed on the value of a deep layer of loose, 
fine soil as a filter-bed that will catch escaping nitrogen and other plant foods. 
The excess water that percolates through 4 feet of 
Loose Soil Prevents fine soil particles loses much of any burden it carries, 
Leaching Loss and this salvaged material is deposited deeply, where 

it is relatively safe from further leaching as well as 
convenient to roots under proper condition. 

It should be understood that 
free nitrogen is not taken right 
out of the air 
Tillage Helps and fed directly 
Nitrification to roots. It has 
to go through 3 
or 4 chemical changes before it 
reaches the stage in which roots 
can take it from the moisture 
films in the soil particles. These 
changes, known to agriculturists 
as nitrification, are important in 
this discussion only because they 
require air, capillary moisture and 
bacterial action. 

The process of nitrification is 
much hastened when soil condi- 
tions are good. In fact, in soil 
that lacks air and which is either 
Very wet or very dry, it is difficult 
to \eep nitrogen in an available 
form, no matter how much organic 
matter may be present. It either 
is liberated and escapes, or it re- 
verts to an unavailable form. 
This is illustrated in muck and 




At Lynchburg, Va., blasting the soil for shade 
and ornamental trees has become a recognized prac- 
tice. Notice the excellent growth of new wood on the 
ends of the limbs of this elm. 

127 



peat, soils that are almost entirely composed of the remains of plants, rich in 
nitrogen in an insoluble form. Therefore, adequate supplies of free nitrogen 
are to be found only in soils that are well and deeply worked. 

The methods of working the soil are unimportant, so long as they are thor- 
ough and effective enough. Deep tillage implements will do good work to a 
depth of 18 inches under favorable conditions. Blasting will do even better 
work to any required depth. The repetition of the full discussions of this 

matter on pages 1 14 and 120 is not necessary here. 
Methods of During years past some friends of soil blasting have 

Working Soil claimed for it certain other advantages that never have been 

proved. It is unnecessary and undesirable to list them in 
this bulletin, for no exact data are available on which to base conclusions. 
Furthermore, whether or not such claims are true is of little importance, because 
of the overwhelming value of the direct physical tillage action of proper soil 
blasting, which cannot be questioned. Soil blasting is intensive deep tillage. 



128 



Treatment of Different Soils 

Practically all clay and loam soils respond wonderfully to tillage blasting, 
requiring only the addition of lime, the required fertilizers and cover crops, of 
course, to make them produce record-breaking crops. But there are a few 
soils that differ in nature from clay and loam to such an extent that intensive 
deep tillage is of no benefit to them. 

One way of making clear the proper treatment for each soil would be to 
describe every important soil in the country, giving its nature and suggestions 
for exactly the sort of tillage best suited to it. For instance, we might describe 
limestone soils, redshale soils, sassafras soils and so on down a long list, making 
clear the types of each soil. This, however, would be a cumbersome way of 
going about the matter. 





Lynchburg, Va., where a great many ornamental trees are set in blasted ground. These 
trees show by the amount of new growth exhibited in the pictures that they have plenty of moisture 
and food. 

Soils are classified by the Government and by agricultural authorities 
largely according to their origin, as is illustrated in the ones named above. 
Yet to the practical orchardist, with a practical problem in fertility and mois- 
ture supply to solve, the vital factor is first the size of the particle and second 
the condition of the soil with respect to amount of organic matter present in 
the particular land he has. Therefore, it seems that the things to talk about 
here are the structure, texture and condition of soils, rather than their origin. 

About 10 types, or degrees of fineness of particle, usually are recognized, 
ranging frcm pure clay, through various degrees of silt and loam, to pure coarse 
sand. The clays have the finest particles; the sand the coarsest. As a general 
rule it can be said that the smaller the particle of the soil the greater the benefit 
it will derive from any sort of intensive tillage. 

The fine particles seem to give up their natural fertility easier than the 
coarse ones— they respond more to proper cultivation. As the size of the 
particles increase, less and less plant food will be released from them under 
any conditions, and less and less improvement will be made by intensive tillage 
in the drainage, moisture storage capacity and nitrogen supply. 

129 



When the particles reach the size of SAND and especially COARSE SAND, 
with little or no clay or loam added, the soil has all the porosity it needs and 
the particles are located so as to give their greatest surface area per cubic foot 
of soil when the ground is packed about as hard as it ever gets. To loosen up 
such a soil decreases its moisture storage capacity, already low, without any 
other effects. Such coarse-grained soils should not be blasted. 

Are composed of the remains of plants mixed with sediment 
Muck Soils deposited by standing water. The material remains muck 

instead of decomposing further and becoming loam, because of 
the absence of air and bacterial activity. They should first of all be drained 
of their excess water by proper ditching. This will leave them porous enough 
for best results without further loosening. 

Vary greatly in structure and condition. Their moisture holding 
Clay Soils capacity is high, and they usually need draining. Some of them 
have clay and nothing but clay, compact and practically water- 
tight from top-soil to a depth beyond the reach of roots. Such a clay soil 
should be broken up and fined to a depth of about 43^ feet under ordinary 
circumstances, as this is about all the depth that can be kept open and porous. 
While in some clay soils the layer of clay may be thin — often only 6 inches — 
in others it is 3 or 4 feet, or even 5 or 6 feet thick. Under the clay there is 
often a layer of gravel or sand. Such soils should be broken up clear to the 
bottom of the clay layer, and if the clay is thin and near the surface, the 
breaking should extend into the layer of earth under it, at least through a total 
depth of 4 feet. 

Also vary greatly in structure and condition, but almost univer- 
Loam Soils sally they require the same sort of deep tillage for planting trees. 

They should be fined and loosened to a depth of at least 4 feet. 
Occasionally loam should be loosened deeper, on account of need for drainage. 
The subsoil of long-cultivated loam generally is very much compacted. These 
soils usually are fairly well drained naturally, but may require special attention 
in this respect. Coarse sandy loams and gravelly loams seldom require deep 
tillage. 

And other layers of tight soil may be found in 
Hardpan, Cemented either clay or loam, and sometimes even in sandy 
Gravel, Bound Loams ground. The particles of the hardpan usually are 
and Sands very fine. This layer of compacted and hardened 

material may be as thin as 3 inches or as thick as 
6 feet. It should be broken entirely through in every orchard where found. 

Does not differ in tillage requirements from soil without stones. 
Stony Land The stones seem to help in moisture storage a little, and in 

orchard soil are not regarded as a detriment if they are small. 



130 



How to Blast Orchard Soil 

Proper preparation of ground for planting trees is little different from 
correct tillage of orchard soil between and under growing trees. The principles 
are the same and the mechanics of the actual blasting differ but little. 

The first care in every case must be to see that the subsoil is dry. THE 

SOIL SHOULD BE AS DRY AS POSSIBLE-the 

Soil Must be Dry drier the better. Unless the subsoil is so dry that it 

has but little plasticity the action of an explosive will 

not give the maximum quality and quantity of tillage results. 

The reason why soil cannot be blasted with proper results when it is damp 
or wet is easily shown. Strike a wet clod with a spade. Instead of loosening 
under the pressure the clod becomes compact and makes a solid lump. Now 
strike a dry clod in the same way and you will crumble it. If it is very dry you 
will pulverize much of it into dust. Damp and wet soil becomes compact under 
pressure. Dry soil crumbles. 

If ground is wet or quite damp when it is blasted, the effect is only to make 
a ball-shaped hole 2 or 4 feet underground, more or less covered with loose 
earth. The soil for about a foot on all sides of the immediate spot where the 
charge of explosive was located will be compressed instead of shattered. The 
sides of the hole, so formed, and the bottom, will be tightly packed. A few 
cracks may extend into surrounding soil, but 95% of the effect of the blast 
will be confined to a sphere 2 or 3 feet in diameter, with positive packing instead 
of loosening. THIS IS NOT GOOD SOIL BLASTING. It will not give the 
benefits that have been described in previous chapters of this bulletin. Except 
in isolated instances it will disappoint anyone who tries it with the expectation 
of good results. 





Th es e two pictures are included to show two things. One: how not to blast tree beds; never permit the blast 
to blow dirt out, as these blasts are doing. Keep the amount of the explosive reduced to the point where the surface 
of the ground will be only heaved. The other: how a blast crumbles dry soil; the ground is drier in the left-hand 
picture, hence the soil crumbles to dust. You can see the stones among this soil, in the air. In the right-hand 
picture the soil is damper, and does not powder as well. See pages 103 and 104 for other pictures, 

131 



The conflicting results from "soil blasting" which have been noted in 
various orchard experiments and tests, and about which much discussion has 
been aroused, have been due largely to variation in the condition of the soil at 
the time of blasting. As might be expected with a new process, the methods 
of practice have not become standardized. There are as surely right ways and 
wrong ways of blasting as of plowing. Much of the blasting of the past few 
years has been done in ways that in the light of present knowledge could be 
expected to give but little if any benefit. 

When the soil is dry at the time of blasting, the effects of the explosion 
reach out many times further than when it is damp, and the breaking and 
fining action of the gases is much more thorough and complete. If any cavities 
are formed underground they can be easily filled by running a shovel into the 
bed of the blast. In actual planting, the loosened dirt should be shoveled out. 

In respect to the time or date of blasting, good results are derived when 

the work is done just before the trees are planted — pro- 

When to Blast vided the ground is dry. It is rather difficult, however, to 

bring the two operations together while doing both justice. 

Trees usually should be planted when the ground is damp or wet. You 
can plant trees in dry ground successfully, however, though you cannot blast 
wet ground successfully under any circumstances. If you plant, in dry ground 
use two or three gallons of water about each tree. ' 

Spring usually is the best season to plant in the North, but blasting ground 
in the spring before too late to plant trees is a matter of luck. Proper condi- 
tions occur at that season only once in several years. Sometimes you can do 
it; more often you cannot. Fall planting usually is not advisable in the North, 
though in the South it often is to be preferred. In fact, in the South, planting 
can be done successfully without interruption from the time the leaves drop in 
autumn till the buds open in the spring. 

All things considered, blasting of orchard soil usually can be done to the 
best advantage in July, August or September, after a prolonged rainless period 
of weather. Sometimes the ground is dry enough in May or June; once in a 
while it is dry enough in October or later in the fall. 

Blasting soil in the summer or fall for planting the following spring is 
entirely successful. The plan has many advantages. The action of sun, air, 
frost, water and other agencies during the winter on the loosened soil results 
in much increase in its fertility and cavities made by the blast become filled. 
A cover crop should be growing during the fall months in the blasted ground, 
whether the tree is planted or not. 

When planting must be done in the spring and the soil blasting has not 
been done the previous fall, it is all right to blast if the subsoil is dry, and will 
conform with the tests given on page 131, but if it is wet, the better plan is to 
plant the trees without blasting, then to blast the soil about them during the 
following summer. This can be done with satisfaction. The details are ex- 
plained on page 1 37. 

The proper position of the charge in the soil depends on the nature of the 
soil. It should be deep enough to break the soil down 4 feet, and in many 
cases the effect of the blasting should extend deeper, 
Depth for Charges even as deep as 6 or 8 feet, but such depths of blasting 
are advised only for a few kinds of trees. Individual 
comments on certain soil conditions are necessary to make clear the proper 
depth for charges. 

It must be understood that intelligent placing of charges depends altogether 

132 



on examination of the soil with an auger or by digging. Without the tests it is 
guesswork. 

The proper depth of the charge depends on the thickness of the hardpan 
layer. In any case the soil should be broken to a depth of 4 feet. 
Hardpan Usually, the layer of hardpan is so placed that the charge should 
be located about % of the way down through it. 
In case the layer of hardpan is thicker than 4 or 5 feet, it is almost impos- 
sible to break it entirely through at a reasonable cost. The charges should be 
placed in such soil about 4 feet deep with the object of loosening and fining a 
section of the soil 4 feet deep, leaving the underlying hardpan intact. But it 
is best to break the hardpan entirely through to a softer, more open layer of 
earth underneath when practicable. 

When there is loose or open ground below a relatively high and thin layer 
of hardpan, the charges of explosive should not be placed so near the bottom 
of the layer that the force of the explosion will escape into the loose ground below 
and only break the hardpan into large chunks instead of crumbling it. The 
remedy is to locate the charge higher in the hardpan, but do not place the charge 
so high in the layer that the blast will break through to the surface of the ground 
without shattering the hardpan to softer ground below. 

CEMENTED GRAVEL and other tight, bound soils usually lie in layers 
similar to hardpan, and should be blasted in a similar manner. 

Clay soils may be composed of solid clay or the clay may lie in thin or 
thick layers. Also the clay may be near the surface or may be covered with 
1 or more feet of loam or sand. When this occurs, the clay, if less than 4 or 5 

feet thick, should be broken 
Clay through to more open soil 
beneath. The placing of 
the charges to do this is precisely 
the same as in hardpan, as de- 
scribed in the previous paragraph. 
Where a thin water-tight layer of 
clay occurs 4 or 5 feet below the 
surface, the charges should be 
placed right down on the clay, 
in order to break it through. 

Loam soils, of all kinds, offer 
simple problems. They may or 
may not have a plowsole. The 
subsoil may be loose or very com- 
pact. In any case 
Loam Soils the charge should 
be about 3 feet 
deep. Loams containing a large 
amount of fine earthy sediment 
are benefited by loosening and 
fining, but the charges should be 
placed well to the surface — say 
within 2 or 23^ feet in depth. 

A typical tree in the orchard of H. M. Magee, When the Subsoil is heavy, as 

Waynesboro, Va. Planted in 1901 in a blasted when of dlstinrtlv rlav nature 

bed, it began fruiting in 1907, yielding V/ 2 bushels w " en ol distinctly Clay nature, 

when 6 years old. The following years its yield was the charges should be placed a 

2%, 3, 10H, 12, 14 and 13%, until 1913. The picture f. 11 A f f J 

shows the condition of the tree in respect to growth. nill f reet deep. 

133 




Shale and slate surface soils, whether of clay, sand or loam type, often 

are underlaid with rock. This rock may be brittle and soft, 

Shale and Slate and may be broken up to give more root space. Place 

charges in the rock as deep as 1 8 inches below the last of 

the loose soil. The charges should be heavier than for blasting hardpan. 

The amount of explosive to use in each charge must be governed by the 
depth at which the charges are placed and the hardness of the soil. A strongly 
cemented hardpan, for instance, will require almost double 
Size of Charges the charge that is proper for a relatively light soil. Clay, 
when heavy, requires almost as much explosive to the 
charge as hardpan, though it shatters under much less force when it verges 
close on having a loamy nature. 

Fortunately, no doubt is necessary about the correct size of the charge 
for any particular soil, as there is an unfailing rule which determines the cor- 
rect amount of explosive to use. After you have made sure of the proper depth 
for the charge by boring or digging into the soil and locating and identifying the 
various layers composing it, use just enough explosive at this depth to break, the 
ground to the surface without blowing out a crater. The surface of the ground 
should be heaved and lifted, especially showing a bulge over the charges, but 
very little of the ground should rise into the air at the time of the blast. When 
the ground is quite dry the explosion will create considerable dust, which will 
float above the surface. 

The usual charge for blasting tree beds will be about half a cartridge of ex- 
plosive (3<4 pound) when the charge is located 3 to 33^ feet deep. At 4 feet, 
24 of a cartridge likely will be required. At 2}^ feet deep the charge likely will be 
only \^ cartridge. These figures 
should be the basis for making the 
first test shots, but after the tests 
the size of the charge should be 
regulated entirely by the results 
noted, as described above. 

It must be remembered that 
some soils require considerably 
heavier charges than the above 
stated ones. It is no rarity to find 
a hardpan condition requiring 
1 -cartridge charges placed at a 
depth of 4 to 4}/2 f eet » and certain 
hardpan and clay conditions re- 
quire the placing of 2-cartridge or 
even heavier charges at depths of 
6 feet. 

In general small charges are 
more desirable than large ones for 
tillage blasting or orchards. The 
usual method of blasting ground 
for trees is to place one charge 
where each tree is to stand. 

The trend of practice among 

those who have Studied the matter A soil auger often can be used to good advantage 

and have had much experience is * raakin f h °J e f *» subsoil charges, particularly in 

aiiuiiuYv..mu u l ij heavy soil. Holes started to a depth of one or two 

to use several light charges placed f ee t with a bar can be finished easily with an auger. 

134 




Number of Charges 
per Tree 



not very far apart rather than one large charge, to do the same work in 
preparing the ground for a tree, or in tilling the ground about one. This is 
particularly applicable in deep clay and hardpan. 

An explosion is necessarily more violent close to the charge. Its fining and 
crumbling effect diminishes as the distance from the 
charge increases, hence 3 small charges placed at 
the corners of a triangle, or 5 small charges dis- 
tributed over an area about the point where a tree 
is to be set, will produce a condition superior to one charge located in the 
center of the area. 

The distance between charges is of course governed by the spacing of the 

trees when only one charge is used in each tree bed. 

Spacing Charges When more than one is to be used for each tree and when 

the ground between the trees is to be blasted, the charges 

should oe so spaced as to brea\ up all the ground. 

When 3 or 5 shots or more are used for each tree or tree bed, the spacing be- 
tween charges should be 6 to 10 feet. In case of blasting the ground between 
trees the charges can be spaced 6, 10 and sometimes even 18 feet apart. The 
only way to determine exactly how far it is best to space them is to dig or probe 
into the ground after 3 or 4 trial shots. Note how far the crumbling and 
pulverizing effect of the blasts extend and space the charges accordingly. 

In ordinary loam the average properly balanced blast will break as far as 
8 or 9 feet away, though the ground at the edges of this circle will not be 
well shattered. When the orchard is large each charge should be relied on for 
its extreme range, but in small orchards, particularly in home fruit gardens, 

where economy in the blasting can 
be a secondary consideration, the 
soils should be blasted with charges 
placed from 6 to 1 feet apart. 

The holes should be made 
straight down. Soil that is dry 
enough to be blasted offers con- 
siderable resistance to a bar or 
soil auger. Ordinarily the subsoil 
bar will make 
Making Holes the hole quicker 
and with less 
work. In stony land the bar must 
be used. Sometimes a good prac- 
tice is to drive the bar down a 
foot or a foot and a half, or as far 
as it will go under a few strokes 
of the sledge, then use the auger 
for the rest of the depth. When 
drilling dry ground with the bar, 
the hole should be filled with 
water. 

The holes should be loaded 
A Mammoth Black Twig apple tree in the Rose in the ordinary way, as explained 

Cliff Orchards, Waynesboro, Va., growing in blasted on p a p e s 148 to 150. Put the 

ground. The tree has set a heavy crop of fruit and r r l • • ,.1 L , 

at the same time made a good growth— see the twig charge OI explosive in the bottom 

ends. To do this the tree must have abundant mois- r .Y i i i • _L t 5 

ture and food available during the growing season. or tne nole . P usn ln aDOUt J 

135 




Loading Charges 



Kind and Grade 
of Explosive 



inches of dirt, but do not pack or tamp it, then insert the 
tamping stick and as you push in more dirt work the 
tamping rod up and down and close the hole up tight to 
the surface, being careful not to kink the fuse or the electric detonator wires. 
The charges can be exploded with cap and fuse or with a blasting machine 
and electric blasting cap. When the charges are close enough together to make 
the breaking overlap at the time of the explosions, it may 
Firing Charges be of advantage to fire them simultaneously, owing to the 
somewhat greater execution developed. This calls for elec- 
tric firing. When the charges are spaced so far apart that they will not break 
all the intervening ground, simultaneous firing is of no advantage. Electric 
firing involves more trouble than fuse firing, and is considerably more expensive. 
The explosive to use for blasting orchard soil invari- 
ably should be a comparatively slow acting one. Since 
the ground always is dry, no waterproof qualities are re- 
quired. Use 20% strength ammonia dynamites. 

Making the holes in the ground is the big labor item. 

Time and Cost Loading and firing labor is small. One man should make 

and load 50 to 100 or more holes per day in loam or silt 

soils in good condition. In certain hardpan soils the same man might make 

less than 50 holes a day. 

The cost of both labor and explosives varies so much from time to time 
and from place to place that to name a definite figure of cost for blasting orchard 
soil is risky. The cost, however, ought not to exceed ten cents per shot, on a 
basis of half a cartridge per charge. 

Computation of the average cost per acre is inaccurate, because no two 
orchards will demand the same treatment. By figuring the cost per tree, or 
per charge, and using the following table to determine the number of trees or 
charges in an acre, you can arrive at about what the acre cost in your orchard 
will be. Nearly every fruit grower knows how many trees he has — knows this 
when he does not know the exact acreage — and the cost for the whole orchard 
easily can be figured on the tree basis. 



40 feet 

35 

30 

25 

20 

18 

15 

12 

10 



apart . 



Number of holes to an acre, 
square method 

27 

35 

50 

70 

110 

135 

195 

305 

435 

680 

1,210 



At various spacings, 
triangular method 

31 

40 

55 

80 
125 
155 
225 
350 
505 
675 
1,600 



It does not cost less to blast tree beds than it does to dig the holes, though 
the blasting may save some labor. The soil can be shoveled out of a blasted 
tree bed quickly, but digging without blasting is a slow job. To make the 
holes for the charges, to load, to fire and to shovel out the dirt, takes about as 
much time as to dig average holes. 

136 



Blasting Soil in Standing Orchards 

To blast the soil in orchards already planted, even when the trees have 
reached full size, is entirely practicable. In fact, this is one of the recognized 
methods of renovating and improving old orchards. 

Precisely the same principles apply to this blasting as to blasting the soil 
in preparation for planting trees. The only difference is that imposed by the 
necessity for avoiding the bruising or tearing of roots. The ground must be 
dry and the charges must be placed at the depth demanded by the nature and 
condition of the soil. 

Ordinarily the best way of going about the work is to put in the ground 
very light charges Q/£ to 3^ a cartridge of explosive) at the proper depth about the 
trees under the end of the limbs. Most of the feeding 
Size and Depth roots likely end nearly underneath that point. Some of 
of Charges the roots within 12 to 15 inches of the charges will be 

broken by the explosions, but beyond this range they will 
not be damaged much or at all. 

Trees that have been planted only three or four years will have limb spreads 
too small to come under this rule. To blast the soil about such trees, keep the 
charges away about 4 to 6 feet from the trunks. Each tree-bed should be blasted 
with at least three charges. 

About large trees the charges should be spaced 8 to 15 feet apart, in order 
to break all the soil. Possibly the blaster should be satisfied with a little less 
surface breaking in a standing orchard than an open field or a garden. The 
correct growing-tree blast will have little visible surface effect. Nearly all of 
its execution will be confined in the ground 2 or 4 feet underground, or deeper. 

It is doubly a mistake to use heavy charges about growing trees. The 
local effect is too severe. Charges of a full cartridge will break and bruise a good 
many roots. But the small charges recommended, will not, as a usual thing, 




Few well-informed orchardists attempt to start a commercial fruit plantation without making 
intercrops pay some or all of .the expenses of caring for the trees. To do this requires that the land 
be productive of the crops planted between the trees, and that the trees themselves grow fast and 
bear soon. Intensive deep tillage helps wonderfully in securing both results. 

137 



break roots farther than a few inches. Beyond 1 or 12 inches the ground will 

be loosened and fined for several feet, without any particular hurt to the roots. 

The ground beyond the ends of the limbs of the trees always should receive 

attention. If you thoroughly and deeply work this soil, the new growth of 

roots will run out to it within a year or two, accomplishing 

Blast Soil what you are after without much pruning of the root sys- 

Between Trees tern. The trees in the average orchard are spaced only far 

enough apart to permit a maximum development of their 

root systems, hence you should skip none of the ground between. 

When blasting the soil under and about large trees, it often is a good plan 
to blast on two sides of each tree one summer, and on the remaining two sides 
the following season. 

In very poor soils the plan of blasting out deep craters between the trees 
sometimes is advisable. This serves the double purpose of permitting greater 
root penetration, improving tilth, and giving a 
Blasting Out Craters chance to establish a reservoir of plant food and 
moisture by filling the hole up with manure, com- 
mercial fertilizer and mellow top soil, mixed together. The roots quickly will 
find such a feeding ground. Be sure to include a big proportion of vegetable 
matter — leaves, grass or straw — with the material used to fill the craters. 

The season when tree blasting had better be done is when the ground is 
dry. The only possible objection to August or September blasting would be 
that it might force a fall growth. To blasting non-bearing 
When to Blast trees in July there is no objection, nor can there be any to 
blasting after the first frosts have come in the fall and the 
trees have ripened their new wood. For bearing trees, the blasting should be 
done as soon as possible after the first frost. 



138 



Good Orchard Soil Management 

Practical orchardists will ask how correct blasting of soil should be fitted 
into the regular tillage schedule. The following suggestions do not make a 
comprehensive outline of the orchard tillage subject, but are intended as a 
series of more or less connected hints on methods of cultivation. 

Trees of any age grow faster when well watered and well fed than when either 
water or food is restricted. The blasting of soil is designed to increase the supply 
of both, hence should result in bigger trees at any age. Other things equal, big trees 
certainly will bear more fruit than smaller trees. They have more bearing wood. 

Whether or not the trees bear sooner in blasted ground than otherwise is 
a matter of condition of the trees when they reach 4 or 5 years of age. If they 
are growing very rapidly they will not bear well. If they are not supplied 
with proper nourishment, they will not bear. The trees that bear young are 
those which have grown vigorously during the first two or three seasons, and 
then receive some sort of check, but which have good food and water condi- 
tions. Lack of moisture in late June or early July may throw the growth of a 
young tree into making fruit buds. Lack of plant food, summer pruning or 
insect attacks may do the same. In any case, you cannot get early bearing 
from trees that are not vigorous, hence to put the soil in condition to produce 
vigorous trees is a step toward early bearing. 

The same soil condition is a preventive of insect and fungus damage to 
trees, in that vigorous trees will not be overcome by an attack of scale, cedar 
rust or other orchard enemies as easily as or quickly as one that is growing slowly. 

In the case of bearing orchards, the man who blasts the soil has every 
reason to expect larger fruit than the man who does not. It gives the trees a 
greater supply of moisture to put into the fruit. The growth, health, and 
vigor of these trees cannot but be improved by the additional supply of plant 
food made available, and instead of declining and deteriorating, the trees should 
become stronger and better each year, unless they have already reached a very 
advanced age. 




The need of intensive deep tillage is greatest when heavy intercropping is practiced in the orchard, 
and it is under such conditions that soil blasting shows its most pronounced results. This is a western 
scene, but so far as soil and weather conditions are concerned, it might be anywhere in the country 
that fruit is grown commercially. 

139 



Tilling the Established Orchard 

If possible, plan for your blasting some months ahead by sowing a heavy- 
rooted cover crop in the spring. This is not essential, but it is desirable. Do 
the blasting in the summer or fall. In July or August, if the spring cover crop 
has not been plowed down before, turn it down and sow another which should 
occupy the ground until the following spring. 

The use of so many cover crops is advisable because organic matter must 
be supplied in plenty to the soil if the correct soil processes are to be continued, 
and a proper condition of granulation is to be brought about and maintained. 
Blasting or other forms of deep tillage and cover crops go together. Blasting 
is not half so beneficial without the heavy growth of roots as with them. 

In the orchard where the clean cultivation system is practiced, plow as 
early as possible the next spring after blasting, and keep the ground harrowed 
every ten days or after every rain until late in June or early in July. Then 
sow a cover crop again. The surface mulch of loose soil conserves the moisture 
while the trees need it. The oncoming cover crop takes up the moisture and 
hastens ripening of soft growth of the trees at the proper time. 

The orchard soil should be limed liberally. The best form of lime to use 
in orchards is the ground raw stone. It should be applied at the rate of 2 tons 
an acre every 3 or 4 years. The first application should be made during the 
summer the blasting is done, though it may be given in the spring before, after 
the ground is plowed for the cover crop. 

The use of cover crops is closely associated with the length of time the 
effects of blasting will last. The deep tillage opens the soil, let us say, to a 
depth of 4 feet. Unless there is something to keep the particles apart, each 
winter and each period of wet weather will see more of them floated together 
into the former compact conditions, but when cover crops are sown the roots 
go down to the bottom of the layer of loosened ground, and act as lightening 
to the soil, making it more and more loamy. When practicable, be particu- 
larly careful to get a good heavy stand of the cover crop plants close up to the 
trunks and all about under the limbs of the trees. 

If the blasted soil is supplied as it should be with vegetable matter in the 
form of roots and cover crops plowed under every year, there is no reason why 
the soil should become compact again for 15 or 20 years. Mere mechanical 
loosening of the soil, whether with plows or explosives, may not keep it loose 
nearly so long. Probably under average conditions, it will be well to repeat 
the blasting every 6 to 10 years. 

The kind of cover crop is important only in two respects. You must grow 
clovers, peas, beans or vetch to get nitrogen. You must grow annual, or bi- 
annual plants instead of perennials, in order to have dead and decaying roots 
in the soil rather than living, growing ones. (Weeds, rye, oats, sorghum, millet 
and many other plants are excellent sources of organic matter). 

Any sort of plant will gather and later liberate some locked-up plant food. 
On this account plants can be called "miners" and "refiners" of slowly soluble 
plant foods. The fact that they do this is another reason why it is important 
to have abundant quantities of roots growing deep into the soil. 

In grass mulched orchards it is well to plow up the sod every 4 or 5 years 
in order to force the roots of the trees down from the surface. Otherwise, they 
will tend to gather just under the grass. The plowing should be done in the fall 
following the blasting, or the next summer. Soil blasting is especially valuable 
and beneficial in a grass mulch system of culture. 

140 



The fertilizing of orchards under a proper system of intensive deep tillage 
is a very simple matter. If you grow legumes as cover crops, you will get much 
nitrogen from the air. Usually, some additional phosphorus, and if available, 
potash should be supplied. If the trees indicate a lack of nitrogen, by showing 
yellow leaves and by other signs well known to most orchardists, use 
a little nitrate of soda, cotton seed meal, or other heavy nitrogen carrier. Lime, 
of course, is needed, but lime should not be considered as a fertilizer. It is 
largely a corrective of sourness and a mellowing agent. 

Planting Trees in Blasted Beds 

Shovel out about a bushel of dirt at the point where the tree is to stand. 
Then with the shovel probe and pry down in the bottom of the hole to see if 
there is any cavity or pot hole left by the blast. If there is a cavity, pack it 
full. If the shovel goes in too easily, work it about to compact the ground. 
Better get in the hole with your feet and tramp the ground a little. If you do 
not settle the loosened ground in this way, the tree will settle considerably 
after planting. In case your trees do settle, it is not the fault of the blasting, 
but of careless planting. The bottom of the hole should be 6 inches lower than 
is proper for the roots. 

Stand the tree in place 6 inches too deep and sprinkle in some fine, mellow 
soil. Work this among the roots. You have three means of doing it— tamping 
among the roots with a stick, working the soil in with your fingers, and shaking 
the tree up and down. The latter is one of the best means, and should never 
be neglected. In the process of alternate lifting and pushing down, gradually 
raise the tree the 6 inches and settle it firmly on a well packed layer of earth 
at the proper depth, which is determined by the dark line about the trunk, 
an inch below the surface of the ground. 

As the dirt fills up about the roots, pack it very hard. Get in with your 
feet and tramp it till you think the roots will not have breathing space. You 
cannot well get it too tight. Sometimes a heavy wooden maul or a broad- 
faced iron sledge is handy for packing the ground about the roots. 

The top 3 inches of ground should not be packed. In fact, it is well to 
go over the planting four days to a week after it is done, with a garden rake, 
and loosen any crust that has been formed on the ground about the trees by 
the drying of rain or dew-soaked surface soil. This will prevent waste of soil 
moisture. At the same time glance along the rows to make sure of the final 
line-up of the trees. 

When the blasting is done in the summer or fall, and the trees are to be 
planted the following spring, some lime may be sprinkled over the ground 
with good effect. It is even better to shovel out the loose earth and sprinkle 
some lime in the bottom of the holes. The lime will help to make the soil more 
mellow. 

Orchard trees should be pruned soon after planting. If they are left with 
high, heavy tops the wind will work the roots loose in their new beds before 
they have had a chance to take hold. By cutting back the limbs properly the 
/ wind is given less chance at the trunks. 

__ Steel bar for making 

^s**"^ holes. 



Soil auger — note 
long point. 



141 



Preparing Charges of Explosives for Firing 

A charge of explosives for the purposes of these directions is considered to 
be all the explosives needed for a single hole with cap and fuse or electric 
blasting cap properly inserted in the cartridge of dyna- 
mite (see pages 143 to 150) and tamped in the 
What a Charge is hole, ready to fire. The preparation of charges is practi- 
cally the same for all sorts of farm blasting. The slight 
variations advisable to suit different kinds of work are not 
enough to call for separate treatment, since the principles are all the same. 

All who use and buy explosives should read the next chapter, beginning 
on page 152, on the nature and actions of explosives. It is only the man who 
understands all the facts mentioned there who will be able to load and blast 
with greatest ease, speed and results. 

Scope of This Chapter 

It is important for everyone who blasts to understand why he does things, 
as well as how to do them. For that reason the following discussion of the 
preparation of charges is made full and complete, with due attention to all the 
important factors involved. Details of any particular part of the operation 
can be found quickly by referring to the heading desired, as given in the index. 

Readers who may not desire a full discussion are referred to the following 
brief outline of the process. 

Be careful that explosives, cap and fuse are in perfect condition. Cut a 
length of fuse sufficient for the hole to be loaded, making the cut clean, with- 
out dragging ends, at right angles. 

Pick a cap from the little tin cap box, carefully, with your fingers, and 
slide it gently on the end of the fuse. With a proper cap crimper fasten the 
cap securely to the fuse, making the crimp close to the open end of cap. Avoid 
twisting or punching the end of fuse against the bottom of cap as well as draw- 
ing it away from the bottom. For wet work waterproof the joint of cap and 
fuse with tallow, soap or other material. Do not use thin grease or oil. 

Next punch a hole at a long slant in the side of the dynamite cartridge to 
be primed. Better use a wooden punch for the purpose. The handle of the 
cap crimper may be used. 

Insert the cap in the hole made as described, tie the fuse in place, and, for 
wet work, waterproof all openings in the cartridge. You then are ready to load. 

Provide space enough in the hole at the proper point to hold the required 
amount of explosives in a bulk that is not too long. Be sure before you start to 
press in the cartridges to the bottom of the hole (see pages 1 35, 1 48) that there is 
enough clearance to permit their easy and certain entrance. Tamp fully and 
firmly up to the top of the hole. 

The charge is now ready to fire, which may be done by pressing the burn- 
ing or flaring head of a freshly scratched match against the powder in the split 
end of the fuse. 

Carrying Explosives and Supplies 

The place to keep the explosives is in the magazine or storage place, and 

not with you in the field. Carry with you in warm weather only enough for the 

job or the day, or in cold weather only as much as can be 

p . kept warm and in condition for firing until you are through 

- _ . . loading. Keep explosives separate from caps. 

or. Explosives ^ gOQ( j way tQ carry t j ie capSj f use anc j sma jj t00 i s i s 

in a basket. Put a piece of blanket in the bottom, to keep 

142 



out dampness when the basket Is on the ground. Some blasters use an 
explosives box for the purpose, putting a wood handle or double wire bale on 
it. The tight wood box probably is a little better than the basket because it 
affords somewhat more complete protection to the contents. 

Whatever the method of carrying the explosives, it should be well pro- 
tected. This consists in keeping the hot sun off it, keeping rain and fog off 
it, keeping it away from dampness of the ground, and keeping it safe from 
meddlesome people and animals. 

Many blasters prepare charges before going to the field, but it is better 
practice to carry along the tools and materials, and to put them together or 
make the primers on the spot after all the holes are made in the ground or 
rock, and when everything is ready for the firing except to put the explosive in 
place. 

These remarks are given as reminders. Full discussion of proper handling 
and storing of explosives can be found on pages 1 67 to 1 69 respectively. 




Tools and Materials Required 

The first step in preparation of charges is to assemble the following; as 
many cartridges of explosive as will be 
required; a sufficient number of blast- 
ing caps; a sufficient quantity of fuse; 
some string; a wood punch with an end 
the size of a cap for about 3 inches; a 
pair of cap crimpers; a pocketknife. 
If the holes are very damp or full of 
water you also will need some tallow 
or other waterproofing material. 



Putting Caps and Fuse Together (Maying 

Primers) 

A handy box for carrying supplies to field. 

Fuse is described as to sizes and 
properties on page 1 66 and caps on pages 1 65 to 1 66. Readers who are not famil- 
iar with them should turn to those pages at this point. Unroll the fuse and cut 
off a length that will be enough, since fuse burns about 2 feet in a minute (there 
are variations — see page 167). 

Three feet will give you ]}/& minutes or a sufficient time to get beyond 

danger under ordinary conditions. The fuse, of course, must 

be long enough to reach out of the mouth of the hole when the 

The Fuse charge is in place. Measure the depth of the hole before you 

cut the fuse. 

Warm cold fuse before attempting to bend it. It may be 
taken into any warm room for the purpose but should be subjected to no heat 
greater than 1 10 degrees. If for any reason you have doubts about the con- 
dition of your fuse, cut off a foot or more and try it without any cap or explo- 
sive. If it will burn properly it is all right. 

Be sure to get fresh ends both for the match and to put into the cap. If 
fuse has been cut for some time into lengths, it is well to cut off short piece? 
from the old ends in order to bring fresh powder right to the tips. 

143 



Cutting the Fuse 



The Cap 



Cut the fuse off squarely across as shown in the diagram. 
The end of the fuse where cut off should be clean and free from dragging 
ends and threads. If it is not cut off clean, part of the 
covering may double over the end of the fuse in the cap 
and keep the spark away from the explosive, causing a 
misfire. Be careful to keep both ends of fuse off damp 
ground and out of puddles of water. 
If the fuse has been mashed, or is too thick to go into the cap easily, do 
not peel off any of the covering. Reduce the diameter by squeezing it with 
the cap crimpers or by rolling it on a smooth surface under a knife blade or 
other smooth implement. Sometimes you can reduce it by rolling it between 
the thumb and finger. 

The very best way to cut fuse is with a combined fuse cutter and cap 
crimper or on a block of wood with a sharp knife. The blade can be pressed right 
through the fuse and will make a clean cut. Be careful to avoid twisting, pinch- 
ing or otherwise knocking the freshly cut end of the fuse about, for you may 
shake out the powder back far enough to cause a misfire. The powder should 
come out flush with end. 

To get one cap out of the tin box in which they came, tilt the box up on 
edge till some of the caps slide forward, and then pick the cap up with your 
fingers. Don't attempt, on penalty of losing a hand, to take a cap out of a 
box by running a nail or a little stick or the fuse into it in the box. Be care- 
ful you do not drop a cap to the ground or floor. 

Turn the cap upside down, to make sure there is no dirt in 
it, and gently slide it on the fuse till the end of the fuse just 
touches the bottom of the cap. Do not ram, press or twist the 
end against the bottom. 

Hold the fuse with capped end up, to keep the cap from 
sliding off, and crimp the cap fast. This you do with the special plier like 

tool called a cap crimper. The 
"crimp" is made by pinching the 
open end of the cap 
tight to the fuse. It 
should be made with- 
in the last quarter 
inch of the open end 
Never make it toward 
the closed end because you might 
disturb the explosive material in 
the bottom of the cap and cause it 
to explode. 

Cap crimpers are supplied by 
all makers of explosives. Order one or more when you buy your explosive. It 
is well to have an extra one about to use in case you lose one on extensive jobs. 
This fastening of the fuse to the cap is one of the points in blasting where 
a great deal of abuse occurs. Blasters think they can take a chance with danger 
or with misfires, and attempt to crimp the caps some other way. Except in 
extreme emergency don't try to crimp a cap with anything except a regular 
crimping tool; but there are times when one may not have a crimper nor be 
in a position to wait till one can be purchased. There is a way out of this 
difficulty — which is to secure a makeshift crimp, with something else than a 
crimper. It is possible to use a pair of pliers, or a small pair of pincers, and ac- 
complish something that may hold the cap on the fuse. The best makeshift 

144 




Crimping 



ofth 



e cap. 



"Crimp" or fasten caps to fuse with a regular 
crimping tool. This tool does the job far better than 
it can be done in any other way. 



crimp is to take a fold of the cap up at one side of the mouth with a pair of close 
fitting, square-nosed pliers. Be careful while doing this that you do not grind 
the end of fuse against the bottom of cap, or pull the end back from the bot- 
tom. If the fuse should »pull away from the bottom of cap a quarter inch, a 
misfire likely would result. 




Waterproofed (tallowed) cartridges ready for loading in wet holes. 



When the charge is to be placed in a dry hole, waterproofing is not needed, 
but in a wet hole the connections between fuse and cap 
must be made water-tight with tallow or soap. Do not use 
Waterproofing grease, because it may unite with the tar in the compo- 
sition of the fuse cover and soften it, when the powder train 
will be ruined. Water in the cap will surely make it worthless. 



Inserting Caps in Explosive 

The best location for a cap in a cartridge of explosive for farm blasting is 
in a hole in the side, about an inch and a half from one end. The best position 
for the cap at this point is at a slant that takes it in from the side toward the 
center, but as near longways, or parallel with the sides of the cartridge, as 
possible. 

145 




Id cutting fuse from col) Taking one cap carefully Insetting fresh end of 

use sharp knife. from box. fuse in cap. 




Crimping cap with the 
cap crimper. 



Fuse tied firmly to cartridge Electric Blasting — Pass the 
with string. doubled fuse wires through 

a hole in cartridge. 




Loop the doubled end of 
fuse wires over end of car- 
tridge. 



Pull loop tight, bend wires 
at cap, punch hole in top of 
cartridge. 

146 



Insert cap in hole, take up 
slack in wires. (Waterproof 
holes if ground is wet.) 



Position of 

Cap in Cartridge 



In other words, when making the hole for the cap in the 
explosive, make it with as long a slant down toward the 
other end of the cartridge as possible. There are reasons 
for this connected with superior or inferior detonation. 
Another method of priming much used is to insert the cap in a hole made 
in the end of the cartridge of explosive, and then to tie the paper about the fuse 
or wires. This is good so long as it is not damaged, but care must be exercised 
not to have the tamping stick interfere with fuse or cap. With side priming 
there is a cushion of the soft explosive between the end of the cartridge and cap. 
End priming always is good provided sufficient care is taken in loading to 
prevent disturbing or displacing the fuse or cap with tamping rod. 

When all the explosive is removed from its wrapper, the cap must be inserted 
in the loose explosive. This should be done by making a hole, as in a cartridge. 
But it seldom pays to take all the explosive out of its wrapper. Nearly always 
you can leave a half cartridge of explosive intact for the cap. 




A good crimp. 



To make the hole for the cap use the handle of the cap crimper or a wooden 
punch just a little larger than the cap. The hole should be large enough to 
let the cap in without much pressing, but should leave no 
air space about the cap. The depth of the hole also is im- 
Making Hole portant. It should be just enough so that the entire cap 
in Explosive can be buried in the explosive, but not any deeper. If it is 
deeper, the cap may be forced on down to the bottom, which 
will leave some of the fuse in contact with the explosive 
(which may cause burning instead of exploding of powder), or the cap may 
be seated just inside the wrapping, leaving an air space at the inside end or bot- 
tom of the hole, which may lower the effectiveness of the explosive. 

When the cap is seated in its hole in the side of the cartridge, the fuse will 

extend up along the cartridge past the near end. 1 1 must be tied in this position, 

so securely that the fuse and the cap will not be pulled 

back in handling or by rubbing against the side of the hole 

Fastening Fuse when the cartridge is pressed down. The best way to 

to Explosive secure it is to wrap a strong string several times below the 

point where the cap is inserted, then give two or three wraps 

about the fuse, and pull tight and tie; or take two loops 

about the fuse and then several wraps about the cartridge. 




Cutting cartridge in two — roll it under knife blade. 

147 



When the foregoing directions have been complied with you have a cartridge 
of explosive primed with a cap and fuse. It is ready to put in the bore-hole 
in the rock or ground. 

Loading Charges in Holes 

You will need a tamping stick. This must be of wood, and had better be 
about the size of a cartridge of explosive, which usually will be \\^ inches in 
diameter, except in case of blockhole blasting of boulders, when a smaller 
cartridge sometimes is needed to go in small drill holes. Never use a metal 
rod for tamping. Make sure that the hole is ready. It must be big enough to 
allow cartridges to slide down easily (except in the case of small holes drilled 
in rock, when the explosive all must be taken out of the 
Tamping Rod wrapping and crumbled and pressed into the hole). Loose 
stones, sharp stones and roots that obstruct the hole should 
be removed with a bar or spoon scraper. This work must be completed before 
starting to load. If obstructions fall into the hole, after some of the explosive 
is in place, don't try to remove it by force. Make another hole at a safe distance 
from the first, put in another charge and fire it. 

Measure the hole with your tamping stick and judge if there is space for 
the required charge at the right point. Nearly always a charge of explosives 

V : H " i " iff 5555 3E5S 55513 IB m£ii&3SSEia5SSSa ■ ,r » sgaa 

The tamping rod should be of wood. 

should be as compact as possible. If one or 2 cartridges are all the explosive 

required, it usually will not hurt to 
put them end to end. But if 3 or more 
cartridges are required, to put them 
end to end makes the charge too long, 
and places the force of the blast else- 
where than where it should be. 

When your judgment tells you 
that the charge should be in a more or 
less round bulk, enlarge the hole at the 
point where the charge should be 
made. Sometimes this can be done by 
scraping it out at the bottom with a 
toe-bar or spoon-bar. Again, if much 
enlarging is required, it is well to use a 
small amount of explosive to secure it. 
This is called springing. To do this 
prime about a quarter of a cartridge as 
usual, and push it to the bottom of the 
hole. Use no tamping. After it is 
fired wait till the hole cools, and you 
will find a cavity large enough for 
your full charge. 

It is better to avoid springing 
holes if you can, on account of the fact 
that the cavity often is enlarged too 

much, and the surrounding earth is loosened so much as to injure confinement. 

(See page 1 56 on detonation). A great deal can be done by scraping the small 

auger hole out to 2 or 3 inches in diameter at the bottom and then causing the 

148 




Slitting the paper wrapping of cartridge to let 
it swell to fill dry holes. 



cartridges to enlarge and fill the hole solidly. To accomplish this enlargement of 
cartridges, slit their wrappings 3 or 4 places lengthwise, from end to end. Then 
press them home with the tamping stick. They will expand and shorten. Four 
to six cartridges in this way can be got into the full length of two. 

Still another way is to take the explosive entirely out of the cartridge 
wrappings, and with the help of a tin or paper tube, such, for instance, as 
calendars are mailed, funnel it down to the bottom of the hole. But neither 
this method nor slitting the cartridges is wise in wet holes. It is true that 
nitroglycerin powders will stand considerable water, but the safe rule in wet 
blasting is to leave the cartridges intact. Ammonia dynamites will not stand 
wetting inside the paper of the cartridges without damage. (Never under any 
circumstances cut, break, unwrap or punch holes in explosive that is frozen. 
You invite an explosion in your hands when you do.) 

When there is more than one cartridge in the charge, place the primed 
cartridge on top of the others— put it in the hole last or next to last— when 
using the cap-and-fuse method of firing. 

Be sure that all parts of the charge are in firm contact. It will not do to 
have air spaces, or dirt, or wrinkled paper between the cartridges. While all the 
powder likely would go off under these conditions, it will not do as much work 
as it should. 

The cartridges of explosive may fit tightly in the holes. In that case do not 
ram or pound them, but press firmly against them, one at a time, with the 
tamping stick. Press the explosive into tight contact with the sides all round, 
at the bottom of the hole. 

Tamping 

Tamping is a necessity and one of the most important parts of the operation. 
The charge should be tightly confined. It is only in springing 
holes and sometimes in digging post holes that no tamping is 
Tamping advisable, and in ditching that the quantity needed is less. 

When the explosive is in place at the bottom of the hole, 
start the tamping by rolling in some loose ground. Keep the 
tamping stick working up and down to seat this ground against the explosive, 
though make no effort to get it tight till there is a few inches or so over the 
explosive. An exception to this rule is in the case of blockhole blasting of boul- 
ders and ledges, when damp clay tamping should be packed solid all the way 
down to the explosives. 

If the tamping is less than this, the best results will not be secured, hence 
deep holes often are necessary for the sake of confinement of charge as well as 
to contain the amount of powder used. 

Hold the fuse to one side with one hand while the tamping stick is worked 
with the other hand. Rake the dirt to the mouth of the hole and be careful to 
get in the hole only earth— not clods, sticks, grass, etc. Be very careful not 
to damage the cover of the fuse with the tamping stick. 

Fill the hole to the top with tamping, and make it tight. The best material 
for tamping is moist clay. Tamping material always is better when made wet 
enough to ball. Use the heaviest earth within reach, and if it is dry, moisten it. 

Firing 

The free end of the fuse will stick out of the hole filled with tamping, 
say about 4 inches. Your remaining work is to set fire to the powder in the 

149 



fuse, till it begins to spit continuously. Split the end of fuse with your pocket 
knife to make it light easily. Put the flaring head of a freshly scratched match 
against the powder exposed by the cut. (See page 159.) 

Preparing Charges for Electric Firing (Maying Primers) 

Up to this point in the directions for preparing charges the text has spoken 
only of caps and fuse. When the firing is to be done with an electric blasting 
machine instead of fuse, you must use electric blasting caps. 

These come from the makers with the wires already fastened in them. 
(See pages 1 65 and 1 66.) They are ready to be inserted in the cartridge of explo- 
sive without any preparation such as ordinary caps and fuse require. 

Make a slanting hole in the cartridge of explosive just as is described on 
pages 145 to 147. Into this insert the electric blasting cap, letting its wires 
project just as the fuse does when fuse is used. Then tie the wires to the car- 
tridge with a string as fuse is tied, to prevent the cap from being pulled partly 
or entirely out of the hole. 





Bad method of fastening wires. Bad position of cap in cartridge, and of cap wires. 

It is better to tie them. 

It is a little difficult to tie the wires tight enough with a string to prevent 
slipping. Another way to fasten them securely is to punch a hole from the 
center of the end of the cartridge in a slanting direction so that it will come out 
at the side two or three inches from the end. Bend back the electric blasting 
cap wires about eight inches from the cap and insert the loops of the doubled- 
over wires in the hole in the end of the cartridge, pushing it out through the side. 
Open out the loop in the wires and pass the loop over the other end of the 
cartridge. Punch another hole in the end of the cartridge a trifle to one side 
of the first hole and straight down toward the center of the cartridge. Insert 
the electric blasting cap in this hole and then take up all slack in the wires. 
The result will be a primed cartridge where the wires do not cross each other 
at any point and the electric blasting cap is lying parallel with the center line 
of the cartridge. A cartridge so primed hangs vertically so that it is possible to 
load it in a vertical bore hole without its lodging against the sides. See page 1 46. 

In fixing wires of electric blasting caps to cartridges, avoid crossing them 
and avoid bending them sharply or in any manner that will break their insulation. 
If the insulation is broken it likely will cause a short circuit, which will result 
in a misfire. Never take a half hitch about the cartridge with the wires. Do not pull 
at the wires and the cap, because to do so may break the fine bridge wire that 
causes the cap to explode when the current goes through. 

Load these primed cartridges the same as is directed for fuse primed charges. 
Be careful to avoid rupturing the insulation on the wires with small stones in 
the hole or with the tamping rod. 

150 



The finishing of the tamping leaves two wires projecting from each hole. 
They must be connected with the blasting machine or other source of current 
with connecting wire and leading wire, in the manner described fully on pages 
161 to 164. Further discussion is not needed at this point. 

Some General Suggestions 

In priming cartridges of explosive with fuse and blasting cap, you must be 
careful to avoid permitting the fuse to touch the explosive. High explosives 
will burn like gasoline or coal-oil. They are very easily set on fire by sparks 
spitting from fuse. When they are burning the explosion will be very much 
weaker than it otherwise would be, and will give off noxious gases. 

A very frequent cause of misfires is the bending, kinking and crooking of 
fuse. This is especially frequent when the cap is inserted in the center of the 
end of the cartridge of explosive and then carelessly forced over against the side of 
the hole by the tamping stick and tamping material. Keep the fuse straight, 
and never under any circumstances lace it through the cartridge of explosive. 
That is a sure cause of trouble. 

If it becomes necessary to remove a cap from a primed cartridge of explosive, 
do it gently and carefully, and unless the cap and fuse are immediately to be 
inserted in another cartridge, destroy them both by lifting a shovelful of earth 
and putting the cap under the ground in the hole, after which light the fuse 
and go away. 

It is better not to lift or carry the primed cartridge of explosive by the fuse 
or wires when it can be helped. When a practice of carrying primed cartridges 
by the fuse is made, misfires and poor explosions will be caused, not every 
time, but often enough to make it wiser not to do so. The cap often is pulled 
back in spite of the tie string. 

Where explosives that are subject to water damage are used in work that 
is wet, matters can be helped by making the cartridges waterproof with tallow, 
parafnne or other suitable material. It is practicable to stop all the seams on 
the cartridges, load and fire without delay, even with explosives that would be 
put out of business if the water got at the actual material instead of only at 
the wrappings of the cartridges. Pay particular attention to waxing or tallowing 
the place where the cap and wires enter the cartridge. 

When doing wet blasting, use every care to keep the outer end of the fuse 
from dropping into the water or from resting on damp ground. The inner 
wrappings of fuse and the powder train itself take up water like a blotter. On 
a very foggy day it is well to keep fuse in a closed box. Mist and rain, of 
course, will damage it. 



151 



Explosives and Blasting Supplies 

The catalogs of manufacturers are not intended to give all the fundamental 
facts about and the differences between the various explosives. To do so 
would take too much space. They give the trade names and the measure- 
ments and weights of cartridges and boxes, demanded by purchasers, and are pre- 
pared on the supposition that blasters and buyers of explosives know what 
they need. This bulletin includes explanations of the names under which 
blasting explosives are made and marketed, outlines their properties, and makes 
clear the work and conditions for which each grade is intended and suited. 

Explosives 
There are scores of different kinds of explosives made and used for blast- 
ing purposes, and many dozens of different names used for them. The most 
familiar name of any explosive in America is dynamite. Other 
names are farm dynamite, quarry powder, contractor's powder, 
Names coal powder, stumping powder, Judson powder, gelatin, blasting 
gelatin, R. R. P., giant powder, blasting powder and dozens of 
others. 
Nearly every one of the explosives designated by these names is made 
in several strengths, and in qualities to suit varying conditions. For this rea- 
son figures and other marks are attached to the names to distinguish the grades. 
In addition to this some of the names are used to designate not only one cer- 
tain explosive but several widely different ones. This is particularly true of 
the names dynamite and powder. The selection of names in the preceding 
paragraph is made for illustrative purposes, and is not to be taken in any sense 
as a recommendation of those explosives for any purpose. The recommen- 
dations are given in detail on other pages. 

All blasting explosives are not made from the same ingredients, and they 
differ a great deal in many other ways than in quality, as quality is generally 
understood. You can buy cornmeal that is good, bad or indifferent, but when 
you buy explosives you will find there are few which can be 
classed as of poor quality. Nearly every standard kind and 
Differences grade is of excellent quality for some particular purpose and 
condition. And practically every one can be classed as of poor 
quality for conditions and purposes to which it is not suited. 
Nor is the difference one of size of cartridge or grain, as the case may be, 
though this is one element. The main differences are ones of strength, quickness 
or speed of gases, sensitiveness, resistance to cold and to water, density, fumes 
and cost. Some explosives are suitable for wet work, and others only for dry 
work; some are adapted to blasting hard, tough rock, others to blasting ground 
only; some freeze when chilled a little; others can be exposed freely without 
freezing. And it should be noted that many of the better explosives of to-day 
have been developed during recent years and are comparatively new. The ex- 
plosive to buy for any particular work is the best one on the market for all 
the conditions involved. 

Black blasting powder has been known and used for several hundred 
years, and it is practically the same to-day as it has been for a long time. It 
is composed of saltpeter or nitrate of soda, sulphur and char- 
coal. It does not vary in strength, and varies little in other 
Explosive properties. 

Ingredients The dynamites and high explosive powders have little or 

no relation to black blasting powder. They depend for their 
explosive force on other explosive chemicals the best known of 
152 



which are nitroglycerin and ammonium nitrate. It is not necessary in this 
brief description to name additional explosive elements. 

The first dynamite was made in Europe by mixing nitroglycerin with a 
light spongy earth, and packing the mixture in paper tubes as cartridges of dyna- 
mite and powder are packed to-day. Nitroglycerin itself is a wonderfully 
efficient explosive when it can be controlled, but it is so sensitive to shock that it 
must be mixed with absorbents and treated to make it safe enough to handle. 

As other explosive chemicals become better understood, it has been found 
of advantage to substitute materials that are explosive for the light earth used 
to absorb the nitroglycerin. And more than that, the nitroglycerin itself has 
been displaced to varying degrees in some of the dynamites by ammonium 
nitrate and other materials. Few blasting explosives contain no nitroglycerin 
at all, but many contain only 4 or 5 per cent, of it. Each of these combina- 
tions of materials, or formula, has its own peculiarities in addition to variation in 
strength, all of which information it is well for a buyer and blaster to 
understand. 

The explosives marketed as "straight dynamites" are made from nitro- 
glycerin. Those made from an ammonium nitrate base are called by many 
manufacturers "ext*-a" dynamites. Gelatin dynamites and blasting gelatin 
are nitroglycerin explosives in which the nitroglycerin has been combined with 
gun cotton. The various special mine, quarry, stumping, farm and other 
miscellaneous dynamites and high explosives on the market are not so named 
that their ingredients can be determined without a statement from their 
makers. 

The power of an explosive and its violence are two different qualities. 

The power, or direct strength, is due to the volume of the gases. If a pound 

of a certain explosive gives, for instance, 1,000 cubic feet 

of gas when completely detonated or fired, while a pound 

Strength and of another explosive gives 500 cubic feet and a pound of a 

Quickness third gives 2,000, the lifting power of each explosive will 

be in direct proportion to its gas volume. 

But the violence of the gases depend, not on their 
volume, but on their speed. If they are comparatively slow in forming and in 
forcing their way out of their confinement they will break out large cracks 
and escape through them, pushing the material aside. If they are very fast 
or quick, they will grind and pulverize everything they come in contact with, and 
throw out the whole side of the confining material, but will not crack it so far. 

The matter can be made clear by comparing a push with a blow of a hammer. 
Both may have equal power, but the effects on a block of wood, for instance, 
at the point where they are applied are very different. The push will move 
the object almost without marking it. The blow may move it, but it is sure 
to leave a mark of greater or less depth, depending on the nature of the ham- 
mer and its speed. A still better comparison, perhaps, is that between the blow 
of a sledge and of light hammer. It is possible to hit a blow of as much power 
or weight with one as with the other, but the material at the point where the 
blow lands with the light hammer will be badly dented, or maybe broken. 
The reason is that the light hammer moves with much greater speed. 

In quarries blasters make use of these facts in order to get the rock broken 
out in pieces of the size preferred. When they want large pieces they use an 
explosive with sufficient power to break the rock, but, comparatively speaking 
with a slow speed of gases; when they want small pieces and much shattering, 
they use an explosive of the same or greater power but with swift and violent 
gas action. 

153 



For each result and for each material a certain power is required and a 
certain quickness of the gases is best. By way of illustration, take soil blasting for 
tillage purposes. There is no object in violently grinding the earth at one spot 
while surrounding earth that might be reached is left untouched. A proper 
explosive for this purpose is one that will have enough pulverizing action, 
that will lift and shake up the soil, and that extends its effects for long distances. 
For an example of the other extreme, take mud-capping rocks. For this work 
the explosive cannot be too violent in action. The gases, backed up by the 
rapidly yielding wall of air behind them, must strike the rock a crushing blow 
in the minimum of time. 

Nitroglycerin and ammonia dynamites, for all practical purposes, are of 
equal strengths when of equal markings. The strength is indicated accurately 
by percentage figures. 

Nitroglycerin explosives are uniformly quicker and more violent in action 
than ammonium nitrate explosives, and the more nitroglycerin there is in the 
explosive the quicker it is. The ammonia explosives are not as quick, in any 
strength, as the corresponding nitroglycerin explosives. Therefore a 50% 
nitroglycerin dynamite is more violent than a 50 % ammonia dynamite, and a 
20% ammonia dynamite is much less violent than a 50% grade. 

When the object is to shatter and reduce to fine fragments the material to 
be blasted, the proper explosive is a quick one, while when the object is to 
lift and shake up the material the best explosive is a slow one. (See table on 
page 156, also detailed recommendations on pages 136, 152 and 156.) But 
there are other factors that must be considered. 

Nitroglycerin explosives resist water better than ammonia explosives, but 
if the cartridge wrappings are not broken or opened, ammonia dynamite or 
powder can be loaded in wet holes with entire satisfaction. The firing should 
not be delayed any longer after loading than necessary, and it is wise to plan 
the work so that it may be done at the longest within a half hour after loading. 
Storage in a damp place will weaken explosives, especially ammonia explosives. 

Gelatin explosives resist water very well, and may be loaded in wet holes, 
or under water, with assurance that they will explode with their full power. 
Blasting gelatin is entirely water-resisting. 

Explosives will freeze, and when in this condition are dangerous, and can- 
not be fired properly, if at all, with a cap of any kind. They must be thawed 
and they must be handled very carefully if they are to be used. On no account 
attempt to cut the wrappings, to break a cartridge or to handle the frozen explo- 
sive in the ordinary way. (See pages 1 57 to 1 59 for directions for thawing.) 

Regular nitroglycerin explosives are quickest to freeze. Others, known as 
"Low Freezing," will stand much lower temperatures without 
causing trouble in this respect. 
Freezing Ammonium nitrate explosives also will freeze, but not quite 

so quickly as nitroglycerin explosives. They too are made on 
both regular and low freezing formulas. The low freezing am- 
monia will stand more cold than the low freezing nitroglycerin. 

The regular explosives will freeze at temperatures of 45 to 50 degrees. 
The low freezing explosives will not freeze and become solid till the thermometer 
gets down below the freezing point of water, and in practice many of them can 
be used right out in the open when the temperature is down to 32° F. for some 
time before starting to freeze. The length of time the powder is exposed to 
the cold has much to do with its freezing. 

The safety point for both low-freezing explosives and regular explosives is 
not a matter of rule, but of watching the explosive. When dynamite is frozen, 

154 



the cartridges will be hard, and when it is partly frozen they may have a mottled 
appearance on outside of the paper wrappings. The hardness may only be in 
spots. When not frozen, the cartridges should be a little soft all over. No 
explosives should be handled much, cut, punched, rubbed, broken or loaded 
when they are frozen. They cannot be exploded satisfactorily and such acts 
are dangerous. 

In cold weather always use the low freezing grade of explosives, for the 
regular grades may freeze in the holes before they can be fired. It is a good plan 
to use the stronger caps, say No. 8 (see page 1 65) in cold weather. When a 
charge of explosive is chilled but not frozen it can be fired satisfactorily by a 
heavier impulse (blow and heat) than ordinary, such as a fresh No. 8 cap gives. 
The low freezing explosives do not differ in action from the regular explosives, 
and are just as efficient. 

The gases of explosives naturally are more or less objectionable when 
breathed. Some of them are poisonous, others are merely disagreeable. When 
explosives are used out in the open the gases are taken up by the air so quickly 
that none of them give any serious trouble, though they do cause headaches if 
the fumes are inhaled. It is only in tunnels and deep shafts where the air is 
confined that the matter of fumes is important, not on farms. 

Special explosives have been developed for tunnel and mine work, but they 
are not important in agricultural work. The only fact about fumes worth know- 
ing in farm blasting is that nitroglycerin explosives either 
in the form of their gases or when absorbed through the 
Other Properties skin will cause headache somewhat quicker than ammonia 
explosives. The so-called fumeless explosives always cost 
more than any ordinary dynamites and are not suited to 
farm work. Farmers will do well to buy grades of explosives suited for their 
special purpose. 

Most dynamite is a light-colored material that looks like fine, sticky saw- 
dust, and it is packed in "sticks" or cartridges made with cylinders of tough 
paper. These cartridges vary in diameter and length. The 
standard is I 1 4 inches in diameter and 8 inches long. This 
Appearance is the size carried in stock by dealers and in the magazines 

of Explosives of the makers. Sizes other than the standard \] ± by 8 inch 
may cost more per pound than the standard owing to higher 
packing cost. 

Dynamite is usually packed in wooden boxes containing 25 pounds or 50 
pounds. A 50-pound box of 20.% ammonia dynamite will contain about 100 
1/4 by 8-inch cartridges. If of 20% nitroglycerin, it will contain about 98 
cartridges. If of gelatin dynamite, it will contain about 88 cartridges. 

A word should be said here about the cost of explosives. No quotations can 
be given because the prices vary in different parts of the country and from time 
to time. The ammonia products usually are cheapest. The cost of course 
follows the percentage strength, the low percentages cheaper and the high per- 
centages dearer. Gelatin explosives cost about the same as straight nitro- 
glycerin explosives. The special explosives for use in mines, tunnels, quarries, 
railroad construction work, etc., often cost more than the explosives recom- 
mended here for farm work. 

In buying explosives look first to getting the one that is best suited to 
the work to be done, and aside from that the cheapest one. There would 
be no object in using a straight nitroglycerin or a gelatin explosive when one 
of the ammonia farm powders would do the work, for the former explosives 
cost much more than the latter. 

155 



To avoid "explosive misfits" it is well to consider carefully the nature of 
the material to be blasted, the conditions of weather, water, etc., and the results 
wanted. The kind of explosives to use depends on these factors. Keeping in 
mind the facts mentioned in preceding paragraphs, the reader will see that there 
is a type of explosive made for almost every condition and kind of work, and 
will understand why one will not suit the work of another. 

As the briefest and clearest way of giving general suggestions for the type 
of explosive best for different agricultural work, a table follows: (Detailed 
recommendations are given on pages 136 and 152.) 

Explosives Recommended for Different Wor\ 

Stone blasting — mudcap Straight nitroglycerin or ammonia dynamite, 

50% or 60%. 
Stone blasting — undermine 

"Snake holing'' To break, same as for mudcapping; to throw 

out, use any dynamite of 20% strength. 

Stone blasting — blockhole To shatter well, any high percentage dynamite; 

to break into large pieces, 20% ammonia 
dynamite. 
Soil blasting — for subsoiling and 

for tree planting 20% ammonia dynamite. 

Ditching — electric firing 20% to 40% ammonia explosives; (nitroglycerin 

is equally effective); in loose dry ground, high 
percentage nitroglycerin explosives. 
Ditching — transmitted detona- 
tion Straight nitroglycerin dynamite, 50' ,', or 60% 

strength. 
Stump blasting — in medium 

and heavy soils, wet or dry. 20% or 30% nitroglycerin or ammonia dyna- 
mite. 
Stump blasting — in dry sand 

and other light soil 40% or 50% nitroglycerin or ammonia dyna- 
mite. 
If you are in doubt as to the best explosives for your particular work it is 
well to write to the manufacturer you prefer, asking which of his grades and 
brands would be most suitable. 

Detonation 

It is well known that black powder is fired by a spark, and that dynamites 

and high explosives cannot be fired by a spark but require a combination of 

shock and heat such as is produced by a detonator. It 

is not so well known that there are great differences in the 

Firing, Exploding nature and effect of the explosion of any dynamite, due 

or Detonating to variations in the way it is fired. 

An explosion of dynamite is the result of a very sudden 

creation of a great volume of gas from a smaller volume 

of explosive. The kind and amount of gases produced by any high explosives 

depend on the kind and amount of shock used to fire the charge, and on its 

confinement. 

156 



The effect of lighting a piece of unconfined dynamite with a piece of fuse 
without a cap on, is that the dynamite will burn fast without exploding and make 
a dense smoke which has a bad smell and produces severe headaches. This is 
simple combustion. If the piece of dynamite is confined closely and lighted in 
the same way it will explode, but will give off similar bad fumes. If a weak cap 
is used on the fuse, or the dynamite is set off by a fall, the dynamite will be 
partially detonated, and explode with considerable force, but it still will give 
off the bad fumes and smoke. The same piece of dynamite fired with a No. 6 
or 8 cap will be completely detonated, and will explode with great violence and 
force, even when unconfined, except by air, and will give off very little smoke. 

The last-named explosion is detonation. It is produced by a violent shock 
in connection with intense heat. Nitroglycerin is 5 times as strong as black 
blasting powder when exploded by fire, and 1 times as strong when detonated. 
This explains the enormous force given by detonation as compared to simple 
explosion. 

But detonation itself is no set thing that always takes place the same. 
There is good, or complete, or full detonation, and there is partial detonation. 
In case of incomplete detonation, or any detonation at a less speed than the 
greatest for any particular explosive, the gases formed are not what they should 
be. For one thing, they are more noxious or poisonous. The more powerful 
and severe the blow delivered by the cap, the more quickly does the chemical 
action take place in the explosive. It is only when high explosives detonate 
with their greatest speed that their maximum power is generated. 

Air spaces about the cap in the cartridge of explosive cushion its blow and 
weaken detonation. It is the nature of the initial detonation of the powder 
right around the cap which governs the nature of the explosion of the whole 
charge. A blaster should understand the importance of setting up complete 
detonation in order to get the greatest amount of force out of explosives. Some- 
times explosives lose as much as 20 % of their effectiveness when fired with weak 
caps. Lack of confinement has a similar effect. Sixty per cent, dynamite 
poorly detonated is less effective than 40 c " well detonated. 

When explosives become chilled it is difficult to detonate them properly 
with the usual cap, hence the advisability of using a very strong cap in cold 
weather — a No. 8. Many of the holes are frequently loaded for some time 
before firing, and even if the powder is soft and normal while charging, it after- 
wards becomes somewhat chilled in the cold ground. 

Throughout this and other bulletins in this series, the 

terms caps and electric blasting caps are used in speaking 

Cap Means of the exploders used to fire the charges of dynamite, although 

Detonator in the field and among manufacturers the same articles are 

called by the terms "detonators," or "electric exploders," or 

"electric blasting caps." 



Thawing Explosives 

It has been pointed out (on page 1 54) that regular explosives chill or freeze 
at temperatures of 45 to 50 degrees. With the increase in the number of low 
freezing explosives that seldom need thawing, the necessity for doing the 
thawing on farms is not as frequent as it used to be. 

Cartridges of frozen dynamite improperly handled are dangerous materials, 
and whenever the temperature is near the freezing point for them, the cartridges 

157 



should be inspected before using to see if they show any of the hardness that 

indicates chilling. If so, handle them very carefully till they are thawed. 

Dynamites will be a little soft to the pressure of your 

thumb when they are not frozen. 

Frozen Explosive Frozen explosives are dangerous because they are 

very much more easily exploded in the course of ordinary 

handling. They are more sensitive to friction and to 

blows of tools. The cartridges may explode when broken in two, when wrappings 

are cut with a knife, when cap holes are punched with a stick, or when they are 

shoved into a hole with a tamping stick. At the same time they are so much less 

sensitive to the direct shock of a detonating cap that they cannot be fired 

properly with a cap. Therefore the rule must be laid down that frozen cartridges 

of high explosives never must be cut or ruptured or used until they are thawed. 

When nitroglycerin freezes it crystallizes, therefore the nitroglycerin in 

dynamite tends to separate from its absorbing materials into small crystals. 

When the dynamite is thawed slowly with cartridges lying on their sides, the 

nitroglycerin is reabsorbed as fast as it liquefies. But when thawed too fast, 

the nitroglycerin is liable to run out of the cartridges before it is reabsorbed. 

Quick thawing will damage explosives a great deal more than they would be 

damaged by freezing followed by long, gradual thawing. 

Thawing is a dangerous operation when not done 
right. It probably is correct to state that more acci- 
dents with dynamite have occurred in the course of 
improper thawing than for all other reasons put to- 
gether. At the same time proper thawing is entirely 
safe. 

Two of the most frequent causes of accidents while 
thawing explosives are in putting the cartridges into 
water or steam, and putting them on hot stoves or stones. 
Water, and especially hot water, forces the nitro- 
glycerin out of the cartridges. The free nitroglycerin 
One type of thawer on goes to the bottom, and explodes at the time of the first 
increase in heat, or first light blow. When cartridges 
of dynamite are laid on hot material the nitroglycerin also runs from the paper 
wrappings and drops of it fall to the stone or metal. 
Causes of This almost always causes an explosion. At about 

Accidental Explosions 350 F. degrees of heat, which is only a little more than 
that of boiling water, the nitroglycerin will explode 
without a shock. 

Examine your explosives a day or so before you are ready to use them, 

and if they show that they are frozen, proceed to thaw 

them in one of the following ways: Use only a DRY warmth. 

Safe Thawing Use no temperature higher than is comfortable to the hand, 

or the limit may be set at 100 or 110 degrees. Use no heat 

of any kind that cannot be controlled with certainty. If 

you do this you will be safe. 

Every large maker of explosives will supply thawing apparatus that is 

safe. Sometimes this is a double kettle arranged so that the cartridges of 

explosives can be placed in the inside vessel, while the outside vessel can be 

filled with warm water and a blanket can be spread over the top. Other more 

elaborate thawers consist of a vessel containing watertight tubes just big enough 

to hold cartridges of explosive, running through a space to be filled with warm 

water. The catalogs describe these ready-made thawers in detail. 

158 




Home-made thawers can be arranged with two buckets, one small enough to 
hang inside the other. Put the cartridges inside the small one and warm water 
around the outside, in the big bucket. Another good way is to put a five-gallon 
can of warm water inside a barrel, or box, and pile the cartridges of explosives in 
the barrel around the can. The top of the barrel should be covered with a 
blanket. Or put the water in the barrel and the explosives in a can or bucket. 
A small closet of course can be used instead of a barrel. A can of warm water 
can be set inside a magazine to keep the temperature up. 

The old-fashioned manure pile method of thawing is reliable 'and safe. 
This consists in burying a box somewhat larger than a box of explosives in fresh 
horse manure, and placing inside it the box of explosives to be thawed. A foot 
or more of manure must cover the box, and a small pipe or tube should be inserted 
for ventilation. The manure must be fresh. Allow at least 10 hours to thaw a 
box of dynamite in this way. Twenty hours is better. 

The box of explosives can be taken into any warm place that is dry, but if 
this is a building you must take your own risk of fire and accident. Watch the 
box and the cartridges to see if the freezing and thawing causes the cartridges to 
leak free nitroglycerin. If any of this leaks out of the car- 
Cartridges on tridges and gets on the floor it must be washed up according 
Sides to directions in paragraphs on storage. (Pages 168 and 169.) 

The cartridges of explosives had better be piled irregularly 
rather than in tiers, for thawing. They will rise in temperature quicker in this 
way. They always must lie on their sides rather than stand on end. 



Electric and Fuse Firing 

The very best way to light fuse is to split the end for an inch or less, and 
stick the burning head of a freshly 
scratched match right against the 

exposed powder at the head of the f\^\-H\ ■fffta^^^N* 

split. This will light the fuse even /f "A* A \ \ M&f&Jitr 

in a strong wind. 

Where there are very many 
fuses to light in succession, as in 
subsoiling, it some- 
Fuse and times is of advantage 
Cap Firing to use a gasoline or 
other torch, holding 
the hot flame under the fuse for an instant. Whatever the method, do not 
leave till you see the fuse spitting sparks and smoke swiftly and regularly. 
Further discussion of fuse firing, except as to its adaptations, is not needed. 

Farmers who have only a few stones or stumps to blast, 
or who are planting a few trees or doing a little subsoiling, 
Electric Firing will not need any other method of firing than by caps and 
fuse. Ditch blasting in ground not watersoaked demands 
electrical firing, while the blasting of large stumps, particu- 
larly if green, and in sandy soil, as well as the blasting of large rocks, is made 
easier, safer and cheaper by electrical firing. For large amounts of almost any 
blasting except that of tree beds, subsoiling and very small stumps and isolated 
small boulders, the purchase of an electric blasting machine and the necessary 
wires is justified by the advantages of the electric methods of firing. 

159 





The primary reason 
for the superiority of 
electric firing over fuse 
firing is that several 
charges may be explod- 
ed at once; the different 
charges will increase 
the effi- 
ciency of 
Advantages each other. 
Thus in 
ditching, 
you can fire many 
a good reel for leading wire. charges in a row and 

make a perfect ditch. In stump blasting several small charges very often 
will take a stump out better than one large charge, and in orchard, and 
garden subsoiling the simultaneous blasts frequently are of advantage. 

Electric firing is more certain when the charges are under water. The 
danger from misfires due to moisture as well as from some other cause is reduced. 
Should misfire of the electric blasting cap occur, you are safe in going to the 
charges as soon as the wire is disconnected from the blasting machine. With a 
fuse you must wait some hours to be safe. When several charges, as for instance, 
several boulder blasts are to be fired, you can make one trip to safety do for the 
lot, instead of having to travel back and forward for each shot. The greater 
safety of electrical blasting is due to the fact that the time of firing a shot is under 
the control of the blaster. Finally, the intelligent and careful use of electric firing, 
with its possibilities of two or more small charges doing the work of one large one, 
and its other economies, will save considerable explosives. 

All the makers of explosives supply electric blasting machines. The ma- 
chines are small boxes of wood or metal, containing a small dynamo with a handle 
that you either push down or twist, depending on the 
type of machine, to operate and to fire the charges. 
Electric Machine The machines are made in various sizes and capacities 

to fire 3, 10, 30, or more charges at once. The 10 
charge machine weighs about 15 pounds. Full direc- 
tions for operating and caring for the machines always accompany them. 

For electric firing, in addition to the machine, you will need electric blasting 
caps, possibly connecting wire and leading wire. The leading wire is copper wire 




Duplex Leading Wire. 'Actual size.) 



large enough to carry the amount of current required for the number of charges to 
be fired simultaneously. It is covered with insulating material, and is made 

strong and durable to stand much use. To make the circuit from 
Wiring the blasting machine to and through the charges and back again, 

you must have two strands of leading wire. It comes from the 

160 



explosive makers in single-strand 
form, which must be doubled, and 
in what they call duplex form, which 
has two strands of insulated wire 
twisted together or wrapped to- 
gether under one cover. 

The two small copper wires that 
are fixed in the electric blasting caps 
(see pages 1 65 and 1 66) should be long 
enough to reach out of the holes. 
They may be 
Electric bought in a vari- 

Blasting Caps ety of lengths, but 

4 or 6 feet are re- Connecting wire comes on spools, 

garded as standard. If the charges are close enough together so the wires can be 
connected, no connecting wire will be needed; but whenever the distance be- 
tween is more, the charges must be connected, and connecting wire is the right 
thing to do it with. There is no particular limit for the distance between charges 
that may be connected for firing together. 





Good connection for electric cap wires. 




Good connection for small cap wires and large leading wire. 



Don't Connect This Way 



A very bad connection — a cause of misfires. 

The diagrams in these pages will show how to make electric wire connections. 
Cut away the insulation on the wire ends and wrap the ends together tight. 
Wrap them for two inches. Looping the wires will not do. Be careful to 
scrape with a knife or stone the wire ends to make them bright before wrap- 
ping them together. Corroded or dirty connections are a cause of misfires. 

If the leading wire gets broken and must be 
Wire Connections spliced, solder the connection after wrapping the 

ends together, then wrap the joint with tape to 

161 




Tape for wrapping joints and broken insulation. 



insulate it. Ordinary tire-tape is good, but a better way is to wrap the joints 

with special rubber tape under- 
neath and to cover this with the 
tire-tape. 

When only one charge is to 
be fired, connect the ends of the 
2 strands of the leading wire to 
the 2 electric blasting cap wires 
and connect the other leading 
wire end to the blasting machine 
posts. The connection with the 
electrical blasting machine should 
be made the last thing before firing, after you are sure that the charges are all 
ready and after every person and animal is out of the way of the flying pieces. 
When the blast is all connected together ready to fire, except attaching the 
leading wire to the machine, give the handle of the machine one or two light 
strokes, to make sure that it is working smoothly and to charge the magnets. 
Then attach the leading wires to the binding posts on the machine, making 
sure that both the binding posts and the wires are bright and clean where they 
come together. Raise the handle of the machine to its full height and push it 
down with speed. When the handle starts on its downward stroke, the pinion 
immediately clutches the armature and starts the generation of current. The 
current, growing stronger as the stroke proceeds, causes considerable resistance 
toward the end of the stroke. The current generated is directly in proportion 
to the speed with which the handle is pushed down, especially just before reach- 
ing the bottom. Any let up toward the bottom will cause a drop in the current 
and may result in misfires. Therefore, make it an invariable rule, whether the 
shot be large or small, to bang the handle down hard and carry the stroke with 
all possible speed to the bottom. Try to knock the bottom out of the box. 
Machines which operate by the twisting of a handle must be handled equally 
quick. 



Very best wire connection, ready for soldering if need be. (Excellent for leading wire. ) 



When more than one charge is to be fired the different charges must be 
connected together. The diagrams will help you to understand how this should 
be done. For nearly all agricultural blasting the connection in one series is the 
best — that is, connecting each charge to the next one and so on until they are 
all joined, with one loose electric blasting cap wire from the two end charges 
of the series. (See diagram A and D, page 1 63.) 

Once in a while, where the series is long and the charges are in a line, you 
can arrange to have the 2 loose wires at the same end of the series by making 
the connection, not to each next charge in the row, but to the one beyond and at 
the farther end doubling back and connecting the missed charges. Do not use 
this method where it involves many splices with connecting wire. 

162 



Method of wrapping wires together to make electrical joint, and taping joint. 



In a bulletin of this size it is impossible to give a comprehensive statement 
of electric firing. But to give some idea, it can be stated that an electric blast- 
ing cap requires 1 to V/i amperes to insure firing. This amount 
Current of current will fire one cap or many in a series. To force this 

Required amount of current through the wires requires a certain voltage, 
the amount depending on the size and length of all the wires, 
and on the joints. One bad or poorly wrapped joint will increase the resist- 
ance of the circuit more than several caps. The voltage of the current required 
to fire any circuit usually can be computed by an expert when the details of the 
wiring system are explained to him. 



~VT 



~W 



~W 



**&- 



-yzr 




J§L 




3fraiqht series connection for 
use with blastmq machine 



D 





Examples of ziq -zaq 
series connections 



Ways of connecting up charges for electric firing. 

163 



Electric blasting machines are constructed to give a sufficient amperage and 
voltage for firing properly the number of caps specified as the capacity of the 
machine when connected in a series. If too many caps, or more than usual 
wiring is connected to any machine, misfires will result. 
Other current can be used in place of that supplied by a 
machine, provided it has enough and not too much 
amperage and voltage. Too great a current will burn out 
wires without firing all the charges. Too little current 
sometimes may fire a part of the charges or none. 

Bare connections at the charges or back along the 
leading wire should be raised off the ground by stones, 
sticks or piles of dirt placed under insulated parts of the 
wires at each side of the splice. During a thunder storm, 
do not stand near any of the charges that have been 
connected. Avoid dragging the leading wire over bare or 
rough ground as much as possible, and particularly avoid 
kinking it. Be careful not to break or tear or scratch the 
insulation of any wires. 

Do not attempt to fire through a long length of leading 
wire wound in a coil or on a reel. The induction, leakage 
or short circuit of current in the coil of wire causes the blasting machine to deliver 
a slow discharge, which is fatal to proper firing. Leading wire that is water- 
soaked or that is covered with mud will lose a considerable part of its current. 




Two post electric blasting 
machine 



Misfires 



Many of the accidents noted each year in blasting operations are the 
result of attempting to examine misfires too soon. If misfires occur with fuse 
firing, stay away from the shot at least 2 hours. It is better to wait until the 
next day, for the spark may linger 24 hours and still cause an explosion. (See 
page 151.) Rock and stump misfires are to be avoided especially. When you are 
firing the charges electrically, you may approach the shot in fifteen minutes 
after an attempt has been made to fire the shot. 

Misfires are due to the following named causes. The remedies for them are 
care in preparing the charges and in loading, the details of which are given in 
the proper chapters. 

With cap and fuse firing, misfires are caused by having the end of fuse 
pulled back a little from the bottom of the cap, by crimping the fuse too tightly 
with a groove crimp and shutting off the spark, by damp or wet fuse, especially 
at the end of the cap, by defective cap, by the cap getting pulled out of the 
explosive, by kinked, damaged, broken or pinched fuse, by failure to light fuse. 
A great many misfires were never fired at all. With electric firing the reasons 
for misfires may be damaged wires in the hole, causing short circuits, defective 
caps, overloaded blasting machine (trying to fire a greater number of electric 
blasting caps than the machine is designed for), cap pulled out of explosive, bad 
wire connection at some point, or broken wire. 

If you find after due time that for some reason the charge cannot be fired 
by lighting the old fuse or by sending current through the wires, you must deal 
with a real misfire. 

The best thing to do is to put in another, lighter charge in a new hole made 
6 to 1 2 inches from the original one. The explosion of the new charge will explode 

164 



the old one. Never touch the tamping in the old hole unless you know just how 
deep it is, or how many inches of it there are above the charge. Once in a 
while the tamping may be dug out of a blockhole misfire. It seldom pays to do 
this in stump blasting, and never in ditching, or soil blasting. At best it is a 
dangerous operation. Mudcap charges can be opened and new primers inserted 
without danger or difficulty. This should be done by removing part of the 
mud at another point, and inserting a new cap and fuse, or electric blasting 
cap, as the case may be. 

Cap (Detonators) 

Blasting caps are little copper tubes closed at one end, \ x /i to 2 inches long 
and something less than a quarter of an inch in diameter. At the bottom is 
placed several grains of a high explosive that is very powerful and exceedingly 
sensitive to heat, shock and friction. This high explosive usually is fulminate 
of mercury, but often is other 
material. They are packed in small 
tin boxes, open end up, usually 100 
to the box. 

The purpose of the blasting 
cap is to supply the shock and 
heat necessary to detonate the 
charge of dynamite to be fired. 
So sensitive is the detonating 
material that it would be impossi- 
ble to handle the little bit of ex- 
plosive in the caps if it were not 
protected by the copper shell. Even 
at that caps must be kept free 
from jars and from heat and sparks 
to avoid premature explosion. 

The strength of caps is care- 
fully regulated by the makers to 
fire the dynamites and powders on 
the market. The explosive material 
with which the caps are loaded is 
such as will deliver a shock and a 
degree of heat of the strength and 
violence required. The caps are 
numbered according to strength. 
All dynamites and powders used for agricultural blasting require at least a No. 6 
cap. If they are chilled a little, but not frozen, they require No. 8. It is the 
part of wisdom to use No. 8 caps all the time, especially for propagated ditch 
blasting, if you can get them. They give you a margin of strength should 
moisture or other causes weaken them in storage. 

Blasting caps must be used with fuse. And before they are inserted in the 
cartridge of explosive they must be fixed to the fuse properly. (See pages 1 44 to 
147.) It is the spark which travels down the fuse that fires the cap. 

Electric blasting caps are made on the same principle as ordinary blasting 
caps. They have the copper tube, the explosive at the bottom, etc., but they 
differ in the way this explosive is fired. Instead of by a powder spark they are 
fired by a red-hot wire that is heated by an electric current. 

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D and E are ordinary blasting caps ; F and G are 
electric blasting caps, often called fuzes. 




Electric blasting cap or fuze. 

Every electric blasting cap has fitted in it 2 small copper wires, which 
must be considered part of the cap. Down near the bottom of the cap is a deli- 
cate bridge of finer wire. The entire arrangement is held in adjustment and 
sealed by a casting of sulphur-like substance. 




E D 
The interior construction of an electric blasting cap or fuze. 

For fuse blasting you must use regular blasting caps, and for electric blasting 
you must use electric blasting caps. It is impossible to substitute one for the 
other. Never pull at the wires in an electric cap. It is dangerous and may loosen 
or throw out of adjustment the arrangement of wires inside. And never try to 
dig out the wires of an electric cap or to dig or to punch the explosive in the 
bottom of a blasting cap. 

Fuse (Safety Fuse) 

Fuse is used for firing black blasting powder and for firing dynamite and 
high explosive powders through the medium of a cap. It is made by enclosing 

within a covering a train of special 
black powder and an inflammable 
cotton string. The spark runs 
down this powder train. 

The powder used in fuse is 
specially made for the purpose, is 
pulverized and is highly compressed 
by the covering of the fuse. The 
covering itself is made of varying 
materials, depending on the condi- 
tions under which the fuse is to be 
used. For dry work it is only 
enough to hold the powder in place 
and to keep the powder train from 
getting broken. For damp and wet 
work it is made waterproof by in- 
Fuse as it comes in roils. creasing the number of layers in 

the covering and by adding varnish, coal tar, as other waterproofing material. 
There are many brands of fuse on the market. In buying fuse you must 
bear in mind the character of your work. For work that is en- 
Grades tirely dry you can use ordinary cotton or hemp fuse with satis- 
faction, if it is large enough to fit a blasting cap snugly. 
For work in damp ground, use a fuse in which the cotton or hemp is covered 
with one layer of waterproof tape or other material. This is called single-tape 
grade or may be known by brand name only. For work where the ground is 
wet, such as in stump and stone blasting in damp or wet weather, use a double- 
covered fuse — fuse that has two layers of tape or other material over the cotton 

166 




covering and waterproofing material added. For work where water covers the 
charges it is best to use fuse with three layers of tape or other material and 
full waterproofing. This is called triple-tape fuse or may have special brand 
names. When buying fuse for general farm work, it is well to get a water- 
proof grade, since it can be used for both wet and dry work. 

Most reliable fuse burns about 2 feet per minute when in perfect condition. 

If it becomes damp.it burns much slower. Cases have been known 

where the spark smouldered in damp fuse for hours without 

Rate of traveling more than a few inches. Another source of uncertainty 

Burning is where fuse has been pinched. It may take the spark a minute 

or an hour or a day to get past the pinched point. 

When fuse is cold, it is hard and brittle, and may crack open 
when unrolled. If it gets too warm, its waterproofing material may penetrate 
to the powder train inside and ruin it; or the covering may first soften and then 
harden, in this condition breaking as though cold when unrolled. If grease is 
allowed on the cover it may combine with the waterproofing and ruin the 
powder inside. 

Handling Explosives 

Dynamites in boxes can be hauled freely in spring wagons or auto truck. 
You should see that no bolt heads or other metal parts project from the wagon 
boxes to strike the boxes of explosives. Sweep all dirt out of the wagon. Have 
the beds clean or covered with straw or blankets. 

Go over your wagon and harness before you load dynamite to make sure 
they will not break down while you have the explosive aboard. Be sure you 
have the hitching straps or tie-ropes along, and do not leave the horses standing 
without tying them securely. Break no colts while hauling explosives. If 
you use a motor, stop it and set the brake tight before you leave the load. In 
driving through a town stay away from dangerous crossings. 

Keep the cartridges of explosive in their original boxes until you are ready to 
use them. Don't have them around loose. In carrying them to the field, use 
a wood basket or a box and not a metal bucket. Always protect explosives from 
all possibility of being reached by falling sparks or from match heads or other 
source of fire. Rain, hot sun and the like must be kept away from explosives. 
Use care to lay cartridges or set the boxes or baskets containing explosives where 
they will not fall down, be blown over by wind or knocked over by careless people 
or by animals. Cattle will eat cartridges of dynamite because of their sweet and 
salty taste. The explosive will make them sick, sometimes kill them. 

Since nitroglycerin often will cause headache when absorbed through the 
skin it is best to wear gloves when handling the cartridges. For this same 
reason some people punch holes for caps in the cartridges with a piece of wood 
rather than with the handle of the cap crimper. 

Caps should not be carried in the same basket or box as explosive, but should 
be carried separately. Take only enough along to do the work in view and 
carry them in the tin boxes they come in. Many serious accidents have been 
caused by blasters having loose caps in their pockets during work or afterwards. 
Sooner or later a chance jar is likely to set them off. When several caps have 
been taken out of the little tin box in which they come the rest will be loose and 
will rattle about. This should be stopped by filling up the empty space with 
paper. 

The handling of caps is not dangerous provided you do it intelligently and 
with care. Keep them safe from any jars or heat. You can sometimes do 

167 



many foolish things with dynamite without serious results to 

yourself, but not with caps. Letting a cap fall to the ground 

Handling or floor likely will cause it to explode. For this reason you 

should keep the caps and explosives apart, in hauling, storing, 

and handling, bringing them together only at the last minute 

before you prepare the charge to be loaded in the hole. One cap can produce 

an explosion powerful enough to tear your hands off. 

Electric blasting caps must be handled with the same care as regular 
blasting caps. All caps must be protected from dampness during handling. No 
trouble will be experienced if you use common sense at every turn, but thought- 
lessness and carelessness in the handling of explosives will cause disaster. Bear 
in mind that when an accident happens with an explosive there is no time to 
save yourself, and no afterthought will prevent serious injury to you. Fore- 
thought is the thing with explosives. In an explosive you are handling an enor- 
mous strength. The fact that it occupies small bulk now should not interfere 
with your imagining it as an enormous engine with power enough to crush you 
easily, but under entire control if you do your part right. 

Storing Explosives and Supplies 

The storing of dynamites on farms offers no serious problems, though it 
may call for some shifting of arrangements to meet proper requirements. The 
explosives must be kept dry. They should be kept cool. This means that 
any ordinary temperature of the air is all right, except that in hot weather 
the room where the explosive is kept should not get warmer than 80 or 90 
degrees. If it is properly ventilated day and night it will not. Probably the 
best common storage place for explosive is in an outbuilding under the floor of 
which the air circulates freely and with a ceiling between the room and the roof. 
It should be strong, and should be provided with a lock. A responsible person 
should have charge of the key at all times. 

The explosive should not be kept in a garret, because the hot sun beating 
down on a roof will raise the temperature under the roof away past the 100 
degree mark. 

Dampness is injurious to explosives, as noted on page 143, and dynamites 
and powders must be kept where moist air will not surround them. The ideal 
storage would be fireproof, but since this is out of the question on the average 
farm, the best that can be done in that respect is to guard against fire. It is 
well to make sure that the explosive is out of reach of any stray or malicious 
bullet that might be fired into it. 

Look to your insurance policies and see whether they provide against the 
storage of explosives in any of your buildings. Store the explosive in a building 
not covered by the insurance. 

Where large quantities of explosives are to be stored as a regular thing, 

or for any length of time, it is advisable to consult the makers 

of explosives or others experienced in their handling in regard 

Magazines to the location and construction of a magazine. A magazine 

can be set up cheaply and can be made fireproof, bullet proof, 

thief proof, well ventilated, dry and safe in every way. It 

should be built of brick. Any explosive maker will furnish plans without 

charge. In any case explosives should be stored at least 50 yards away from 

any other buildings and from roads or railroads. 

168 



Blasting caps of any kind must not be stored with dynamite or powder. 

Fuse is not explosive and can be stored with dynamite or powder. 

p Blasting caps are even more subject to damage by moisture than 

P explosive and must be stored accordingly. Caps must not be allowed 

to become heated. 

A statement of the ways in which explosive deteriorates will help in 

selecting a proper storage place for it. In temperatures higher than 80 degrees 

troubles may begin. Long continued temperatures of 

90 to 100 degrees may cause the nitroglycerin to leak 

Deterioration out of the absorbing material and to gather inside the 

wrapping on the lower side of the cartridges, or may 

even cause it to leak out of the wrappings through the 

boxes and to the floor. 

Strict watch should be kept of the cartridges and the boxes to catch any such 
condition. If leakage occurs, turn the explosive over and reduce the temper- 
ature. Burn the empty boxes one or two at a time out away from buildings, 
and scrub the floor where the leakage occurred with a strong solution of sal 
soda. This will decompose the nitroglycerin. If it becomes necessary to de- 
stroy a little explosive without detonating it, the job can be done by immersing 
it until dissolved in such a solution, stirring it gently with a wood paddle. 

If the cartridges feel smeary it is possible they are leaking. The test is to 
lay them on white paper for a little while. If they are leaking they will stain the 
paper, otherwise not. 

At a temperature of 105 degrees nitroglycerin explosives will lose 10' „ of 
their strength in a few days by evaporation. Repeated freezing and thawing 
is bad for explosives, especially if the thawing is /apid. Slow thawing will not 
damage them. After explosive once is frozen and thawed, it will freeze much 
easier again. 

When stored for many months explosives are liable to decomposition of 
some of their elements, especially if they gel: damp or too warm. One of the 
marks of this is greenish stains inside the cartridge wrappings. No length of 
time can be stated for the keeping of explosives, because it practically all de- 
pends on conditions. Under favorable conditions most dynamites and powders 
will remain in good shape for years. Again, a month of improper storage will 
ruin them and make them dangerous to handle. They develop troubles sooner 
in the light than in the dark. 

Deteriorated explosives are likely to be dangerous — far more so than normal 
explosive. Keep watch over what you have in stock. Maintain proper condi- 
tions as far as possible, but if they show troubles do not hesitate to condemn 
them. 

Shipping Explosives 

The shipping of high explosives is controlled by the Interstate Commerce 
Commission, and the rules and regulations are very strict and rigid. Most of 
them are embodied in an Act of Congress of March 4, 1909, and violations are 
punishable with fines of not more than $2,000, or imprisonment for not more than 
eighteen months, or both. The person making the shipment is responsible. 

A copy of the rules and regulations can be secured from the Bureau of 
Explosives, 30 Vesey Street, New York City, or can be read at any freight 
station where there is an agent. 

The rules provide that no explosives (other than certain exceptions named) 
shall be carried on any train, boat, trolley, or other vehicle carrying passengers 

169 



for hire, and that no explosives under deceptive or false markings or under- 
standing shall be delivered to a common carrier; and further, that all other 
regulations shall be complied with. 

In shipping by railroad no caps or detonators of any kind can be sent in 
the same car with explosives. In practice the railroads usually send them by 
another train, which works out to be another day in the cases of nearly all 
shipments. This is responsible for some delay in delivery of explosive ship- 
ments. Do not expect to have explosives come through as quickly as you would 
other freight. 

Explosives cannot be shipped by express or by mail, but are sent by freight. 
The railroad company is required to place the packages in a certain way inside 
the car and to brace them with lumber. In case of car-lot shipments the shipper 
must furnish this lumber and do the bracing. 

The regulations provide that railroads must have 24 hours' notice of ship- 
ment of explosives, and that shipments must be removed from the receiving station 
within 24 hours of their arrival there. The packages must be plainly stenciled 
with the name of shipper and consignee, and bilL of lading must conform with 
certain specifications. 

Empty boxes which once have contained explosives must never again be 
used for shipments of any kind. Farmers who have attempted to ship vegetables 
or other farm products in such boxes have unwittingly gotten themselves into 
trouble on account of this regulation more than once. 

Danger and Safety 

Modern explosives have been developed to the point where they need not 
be feared by anyone who handles them intelligently. Speaking in a comparative 
way, they may be used with no greater dangers than there is in the using of 
horses, mowers, traction engines, sawmills, or other farm equipment, or than 
there is in using shotguns or rifles. 

The general use of explosives on farms is so new that many people dis- 
trust them more because of their newness than from a clear understanding of 
any actual dangers their use may hold. A review of what the dangers are may 
help users of explosives to avoid them, and may help to build up the reader's 
belief in the safety of explosives. 

There is some danger in the handling and transporting of explosives, but 
it depends very largely on the exposure of the dynamite or powder to heat, 
flame, sparks, blows and friction. The directions say to keep explosives dry, 
to keep them at a temperature less than 90 or 100 degrees F., to keep them 
safe from sparks, and to avoid blows and shocks. If these directions are followed 
there will be few accidents. 

Probably the most common cause of accidents with explosives lies in viola- 
tion of some of these primary rules while thawing frozen cartridges of dynamite. 
Freezing makes the high explosive less sensitive to the simple direct shock 
of a blasting cap, unaccompanied, as it is, by any friction. But at the same 
time freezing makes the explosive more sensitive to friction in any form. 

For this reason, though a frozen cartridge of dynamite cannot be fired prop- 
erly by a blasting cap, it is very likely to be fired prematurely by a chance light 
blow from any object touching it, by your slitting the wrapping paper with a 
knife, by breaking the cartridge in two, or by attempting to punch a hole into it to 
insert a cap. (These operations are entirely safe when the explosive is normal.) If 
the cartridge is dipped in warm water or exposed to steam, or is laid on anything 
which is warmer than about 125 degrees, free nitroglycerin likely will leak out 

170 



and fall in drops. And one drop of nitroglycerin falling only a few inches may be 
exploded itself and may explode all dynamite that is near it. 

Throughout the entire course of handling the explosive, from the freight 
station to the hole in the stone or the ground, you should remember the five 
cautions which will be repeated: Keep it dry, keep it cool, keep it away from 
sparks and flame, and keep it safe from blows and friction. Be careful — as 
careful as you would in driving a big automobile or a traction engine. Then 
you will be secure from any accidents, and explosives will be safe to handle. 



171 



